…#10134)

Note:
* This change to the FFI interface for proxy adaptation. And the related
issue is currently suspected to potentially cause fluctuations in
LearnerRead latency in some cases.
#9841,
#9882
* This change to the FFI interface for proxy adaptation
#9893
* Fix stale read can not eliminate the learner read
#10132


### What problem does this PR solve?

Issue Number: ref #4982, close
#10046

Problem Summary:
 update proxy to raftstore-proxy-8.1
 Proxy PR: 
 Including:\nSubmodule contrib/tiflash-proxy caa7a0c1dd..96545a2632:
  > Fix safe ts not updated (#429) (#434)

The leader_safe_ts, self_safe_ts are always 0 in the TiFlash side,
making TiFlash can not eliminate the learner read on region without any
updates.

### What is changed and how it works?

For detailed reasons why safe_ts failed to be updated, checkout the
description on pingcap/tidb-engine-ext#429.

### Check List

Tests <!-- At least one of them must be included. -->

- [ ] Unit test
- [ ] Integration test
- [x] Manual test (add detailed scripts or steps below)
- [ ] 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

<!-- bugfix or new feature needs a release note -->

```release-note
Fix the issue that `SELECT ... AS OF TIMESTAMP` can not eliminate the learner read on TiFlash as expected
```

---------

Signed-off-by: Calvin Neo <calvinneo1995@gmail.com>
Signed-off-by: JaySon-Huang <tshent@qq.com>
Signed-off-by: CalvinNeo <calvinneo1995@gmail.com>
Co-authored-by: Calvin Neo <CalvinNeo@users.noreply.github.com>
Co-authored-by: Ti Chi Robot <ti-community-prow-bot@tidb.io>
Co-authored-by: Calvin Neo <calvinneo1995@gmail.com>