Relates elastic#35975
Relates elastic#39006

With this change, we won't wait for the local checkpoint to advance to
the max_seq_no before starting phase2 of peer-recovery. We also remove
the sequence number range check in peer-recovery. We can safely do these
thanks to Yannick's finding.

The replication group to be used is currently sampled after indexing
into the primary (see `ReplicationOperation` class). This means that
when initiating tracking of a new replica, we have to consider the
following two cases:

- There are operations for which the replication group has not been
sampled yet. As we initiated the new replica as tracking, we know that
those operations will be replicated to the new replica and follow the
typical replication group semantics (e.g. marked as stale when
unavailable).

- There are operations for which the replication group has already been
sampled. These operations will not be sent to the new replica.  However,
we know that those operations are already indexed into Lucene and the
translog on the primary, as the sampling is happening after that. This
means that by taking a snapshot of Lucene or the translog, we will be
getting those ops as well. What we cannot guarantee anymore is that all
ops up to `endingSeqNo` are available in the snapshot (i.e.  also see
comment in `RecoverySourceHandler` saying `We need to wait for all
operations up to the current max to complete, otherwise we can not
guarantee that all operations in the required range will be available
for replaying from the translog of the source.`). This is not needed,
though, as we can no longer guarantee that max seq no == local
checkpoint.

Relates #39000
Closes #38949

Co-authored-by: Yannick Welsch <yannick@welsch.lu>

With this change, we won't wait for the local checkpoint to advance to
the max_seq_no before starting phase2 of peer-recovery. We also remove
the sequence number range check in peer-recovery. We can safely do these
thanks to Yannick's finding.

The replication group to be used is currently sampled after indexing
into the primary (see `ReplicationOperation` class). This means that
when initiating tracking of a new replica, we have to consider the
following two cases:

- There are operations for which the replication group has not been
sampled yet. As we initiated the new replica as tracking, we know that
those operations will be replicated to the new replica and follow the
typical replication group semantics (e.g. marked as stale when
unavailable).

- There are operations for which the replication group has already been
sampled. These operations will not be sent to the new replica.  However,
we know that those operations are already indexed into Lucene and the
translog on the primary, as the sampling is happening after that. This
means that by taking a snapshot of Lucene or the translog, we will be
getting those ops as well. What we cannot guarantee anymore is that all
ops up to `endingSeqNo` are available in the snapshot (i.e.  also see
comment in `RecoverySourceHandler` saying `We need to wait for all
operations up to the current max to complete, otherwise we can not
guarantee that all operations in the required range will be available
for replaying from the translog of the source.`). This is not needed,
though, as we can no longer guarantee that max seq no == local
checkpoint.

Relates #39000
Closes #38949

Co-authored-by: Yannick Welsch <yannick@welsch.lu>

With this change, we won't wait for the local checkpoint to advance to
the max_seq_no before starting phase2 of peer-recovery. We also remove
the sequence number range check in peer-recovery. We can safely do these
thanks to Yannick's finding.

The replication group to be used is currently sampled after indexing
into the primary (see `ReplicationOperation` class). This means that
when initiating tracking of a new replica, we have to consider the
following two cases:

- There are operations for which the replication group has not been
sampled yet. As we initiated the new replica as tracking, we know that
those operations will be replicated to the new replica and follow the
typical replication group semantics (e.g. marked as stale when
unavailable).

- There are operations for which the replication group has already been
sampled. These operations will not be sent to the new replica.  However,
we know that those operations are already indexed into Lucene and the
translog on the primary, as the sampling is happening after that. This
means that by taking a snapshot of Lucene or the translog, we will be
getting those ops as well. What we cannot guarantee anymore is that all
ops up to `endingSeqNo` are available in the snapshot (i.e.  also see
comment in `RecoverySourceHandler` saying `We need to wait for all
operations up to the current max to complete, otherwise we can not
guarantee that all operations in the required range will be available
for replaying from the translog of the source.`). This is not needed,
though, as we can no longer guarantee that max seq no == local
checkpoint.

Relates #39000
Closes #38949

Co-authored-by: Yannick Welsch <yannick@welsch.lu>

Since #39006, we should either remove `testWaitForPendingSeqNo` 
or adjust it not to wait for the pending operations. This change picks 
the latter.

Relates #39006

Since #39006, we should either remove `testWaitForPendingSeqNo` 
or adjust it not to wait for the pending operations. This change picks 
the latter.

Relates #39006

Since #39006, we should either remove `testWaitForPendingSeqNo` 
or adjust it not to wait for the pending operations. This change picks 
the latter.

Relates #39006

Since #39006, we should either remove `testWaitForPendingSeqNo` 
or adjust it not to wait for the pending operations. This change picks 
the latter.

Relates #39006

Before this change, closed indexes were simply not replicated. It was therefore 
possible to close an index and then decommission a data node without knowing 
that this data node contained shards of the closed index, potentially leading to 
data loss. Shards of closed indices were not completely taken into account when 
balancing the shards within the cluster, or automatically replicated through shard 
copies, and they were not easily movable from node A to node B using APIs like 
Cluster Reroute without being fully reopened and closed again.

This commit changes the logic executed when closing an index, so that its shards 
are not just removed and forgotten but are instead reinitialized and reallocated on 
data nodes using an engine implementation which does not allow searching or
 indexing, which has a low memory overhead (compared with searchable/indexable 
opened shards) and which allows shards to be recovered from peer or promoted 
as primaries when needed.

This new closing logic is built on top of the new Close Index API introduced in 
6.7.0 (#37359). Some pre-closing sanity checks are executed on the shards before 
closing them, and closing an index on a 8.0 cluster will reinitialize the index shards 
and therefore impact the cluster health.

Some APIs have been adapted to make them work with closed indices:
- Cluster Health API
- Cluster Reroute API
- Cluster Allocation Explain API
- Recovery API
- Cat Indices
- Cat Shards
- Cat Health
- Cat Recovery

This commit contains all the following changes (most recent first):
* c6c42a1 Adapt NoOpEngineTests after #39006
* 3f9993d Wait for shards to be active after closing indices (#38854)
* 5e7a428 Adapt the Cluster Health API to closed indices (#39364)
* 3e61939 Adapt CloseFollowerIndexIT for replicated closed indices (#38767)
* 71f5c34 Recover closed indices after a full cluster restart (#39249)
* 4db7fd9 Adapt the Recovery API for closed indices (#38421)
* 4fd1bb2 Adapt more tests suites to closed indices (#39186)
* 0519016 Add replica to primary promotion test for closed indices (#39110)
* b756f6c Test the Cluster Shard Allocation Explain API with closed indices (#38631)
* c484c66 Remove index routing table of closed indices in mixed versions clusters (#38955)
* 00f1828 Mute CloseFollowerIndexIT.testCloseAndReopenFollowerIndex()
* e845b0a Do not schedule Refresh/Translog/GlobalCheckpoint tasks for closed indices (#38329)
* cf9a015 Adapt testIndexCanChangeCustomDataPath for replicated closed indices (#38327)
* b9becdd Adapt testPendingTasks() for replicated closed indices (#38326)
* 02cc730 Allow shards of closed indices to be replicated as regular shards (#38024)
* e53a9be Fix compilation error in IndexShardIT after merge with master
* cae4155 Relax NoOpEngine constraints (#37413)
* 54d110b [RCI] Adapt NoOpEngine to latest FrozenEngine changes
* c63fd69 [RCI] Add NoOpEngine for closed indices (#33903)

Relates to #33888

Backport support for replicating closed indices (#39499)
    
    Before this change, closed indexes were simply not replicated. It was therefore
    possible to close an index and then decommission a data node without knowing
    that this data node contained shards of the closed index, potentially leading to
    data loss. Shards of closed indices were not completely taken into account when
    balancing the shards within the cluster, or automatically replicated through shard
    copies, and they were not easily movable from node A to node B using APIs like
    Cluster Reroute without being fully reopened and closed again.
    
    This commit changes the logic executed when closing an index, so that its shards
    are not just removed and forgotten but are instead reinitialized and reallocated on
    data nodes using an engine implementation which does not allow searching or
     indexing, which has a low memory overhead (compared with searchable/indexable
    opened shards) and which allows shards to be recovered from peer or promoted
    as primaries when needed.
    
    This new closing logic is built on top of the new Close Index API introduced in
    6.7.0 (#37359). Some pre-closing sanity checks are executed on the shards before
    closing them, and closing an index on a 8.0 cluster will reinitialize the index shards
    and therefore impact the cluster health.
    
    Some APIs have been adapted to make them work with closed indices:
    - Cluster Health API
    - Cluster Reroute API
    - Cluster Allocation Explain API
    - Recovery API
    - Cat Indices
    - Cat Shards
    - Cat Health
    - Cat Recovery
    
    This commit contains all the following changes (most recent first):
    * c6c42a1 Adapt NoOpEngineTests after #39006
    * 3f9993d Wait for shards to be active after closing indices (#38854)
    * 5e7a428 Adapt the Cluster Health API to closed indices (#39364)
    * 3e61939 Adapt CloseFollowerIndexIT for replicated closed indices (#38767)
    * 71f5c34 Recover closed indices after a full cluster restart (#39249)
    * 4db7fd9 Adapt the Recovery API for closed indices (#38421)
    * 4fd1bb2 Adapt more tests suites to closed indices (#39186)
    * 0519016 Add replica to primary promotion test for closed indices (#39110)
    * b756f6c Test the Cluster Shard Allocation Explain API with closed indices (#38631)
    * c484c66 Remove index routing table of closed indices in mixed versions clusters (#38955)
    * 00f1828 Mute CloseFollowerIndexIT.testCloseAndReopenFollowerIndex()
    * e845b0a Do not schedule Refresh/Translog/GlobalCheckpoint tasks for closed indices (#38329)
    * cf9a015 Adapt testIndexCanChangeCustomDataPath for replicated closed indices (#38327)
    * b9becdd Adapt testPendingTasks() for replicated closed indices (#38326)
    * 02cc730 Allow shards of closed indices to be replicated as regular shards (#38024)
    * e53a9be Fix compilation error in IndexShardIT after merge with master
    * cae4155 Relax NoOpEngine constraints (#37413)
    * 54d110b [RCI] Adapt NoOpEngine to latest FrozenEngine changes
    * c63fd69 [RCI] Add NoOpEngine for closed indices (#33903)
    
    Relates to #33888

Since #39006 we should be able to complete a peer-recovery without
waiting for pending indexing operations. Thus, the assertion in
testDoNotWaitForPendingSeqNo should be updated from false to true.

Closes #39510

Since #39006 we should be able to complete a peer-recovery without
waiting for pending indexing operations. Thus, the assertion in
testDoNotWaitForPendingSeqNo should be updated from false to true.

Closes #39510

Since #39006 we should be able to complete a peer-recovery without
waiting for pending indexing operations. Thus, the assertion in
testDoNotWaitForPendingSeqNo should be updated from false to true.

Closes #39510

Since #39006 we should be able to complete a peer-recovery without
waiting for pending indexing operations. Thus, the assertion in
testDoNotWaitForPendingSeqNo should be updated from false to true.

Closes #39510