expr: fix instr function get stuck

[Yisaer]

Signed-off-by: yisaer [email protected]

What problem does this PR solve?

Issue Number: close #33367

Problem Summary:

What is changed and how it works?

switch off instr pushing down in tikv in order not to block release 6.0 until we find out reason later

Check List

Tests

• Unit test
• manual test

use test;
source [test.txt](https://github.com/pingcap/tidb/files/8338139/test.txt);

select col1, instr(col1, substr(col1, 3)) from PK_RCP9283 where instr(col1, substr(col1, 3)) >= instr("轜廞豑悒笡ç梎尠理襟", substr("轜廞豑悒笡ç梎尠理襟", 3));

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• hawkingrei
• rebelice

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[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/73f52cc4943d2d7edf1320b0339be452dbdbcb96

[Yisaer]

/merge

[Yisaer]

/run-mysql-test

[Yisaer]

/merge

[hawkingrei]

/check-issue-triage-complete

[Yisaer]

/merge

[ti-chi-bot]

@Yisaer: /merge in this pull request requires 2 approval(s).

In response to this:

/merge

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[hawkingrei]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 73f52cc

[ti-srebot]

cherry pick to release-6.0 in PR #33389