ParallelPrehandle: executeParallelTransform could return Aborted if there is ErrUpdateSchema (release-7.5)

[CalvinNeo]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiFlash version? (Required)

[JaySon-Huang]

@CalvinNeo Can you add more description about this issue?

[CalvinNeo]

In master,

tiflash/dbms/src/Storages/KVStore/MultiRaft/PrehandleSnapshot.cpp

Line 206 in b30c1f5

res = ReadFromStreamResult{.error = abort_reason.value(), .extra_msg = "", .region = new_region};

will replicate reason when abort.

However, release-7.5 will not.

So if the result is errupdateschema and aborted, and aborted is handled the first, then prehandle will not retry

[CalvinNeo]

In 7.5, parallel prehandle is not enabled, so the severity is moderate.

[CalvinNeo]

See #8246