What problem does this PR solve?

Issue Number: close #9854

Problem Summary:

When we try to add a vector index on a relative large table, there are much useless logging under debug level

• After DDL owner try to add a vector index, the tidb ddl owner will get the add index progress by fetching system.dt_local_indexes from all tiflash instances
• StorageSystemDTLocalIndexes::read call getLocalIndexesStatsFromStorage. For non-inited DeltaMergeStore, the function calls genLocalIndexStatsByTableInfo -> initLocalIndexInfos -> generateLocalIndexInfos and generate useless logging like "Local index info does not changed, ..." for each StorageDeltaMerge. This will cause much debug logging when there are lots of tables in the cluster

What is changed and how it works?

* Move the logging from `generateLocalIndexInfos` to `DeltaMergeStore::applyLocalIndexChange`. Reduce logging that is not cause by DDL changed
* Return the keep/added/dropped index ids in `LocalIndexInfosChangeset` and generate the changeset logging string by `LocalIndexInfosChangeset::toString`

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

Deploy a cluster with tiflash and enable debug level logging
Load a dataset with 1m vector data
Add vector index and wait

• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None