expression: implement regexp_substr function pushdown

[xzhangxian1008]

What problem does this PR solve?

Issue Number: close #39535

Problem Summary:

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• 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

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• YangKeao
• windtalker

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After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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[xzhangxian1008]

/cc @hawkingrei @windtalker

[windtalker]

LGTM

[YangKeao]

The corresponding TiFlash implementation is here: https://github.com/pingcap/tiflash/pull/6316/files, right?

[YangKeao]

LGTM

[hawkingrei]

/merge

[ti-chi-bot]

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

Commit hash: 850dd8c

[xzhangxian1008]

The corresponding TiFlash implementation is here: https://github.com/pingcap/tiflash/pull/6316/files, right?

yes

[sre-bot]

TiDB MergeCI notify

🔴 Bad News! New failing [1] after this pr merged.
These new failed integration tests seem to be caused by the current PR, please try to fix these new failed integration tests, thanks!

CI Name	Result	Duration	Compare with Parent commit
idc-jenkins-ci-tidb/integration-ddl-test	🟥 failed 1, success 5, total 6	4 min 47 sec	New failing
idc-jenkins-ci-tidb/integration-common-test	🔴 failed 1, success 16, total 17	33 min	Existing failure
idc-jenkins-ci/integration-cdc-test	🔴 failed 1, success 39, total 40	25 min	Existing failure
idc-jenkins-ci-tidb/common-test	🔴 failed 1, success 10, total 11	11 min	Existing failure
idc-jenkins-ci-tidb/sqllogic-test-2	🟢 all 28 tests passed	6 min 41 sec	Existing passed
idc-jenkins-ci-tidb/tics-test	🟢 all 1 tests passed	6 min 8 sec	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-1	🟢 all 26 tests passed	5 min 57 sec	Existing passed
idc-jenkins-ci-tidb/mybatis-test	🟢 all 1 tests passed	3 min 47 sec	Existing passed
idc-jenkins-ci-tidb/integration-compatibility-test	🟢 all 1 tests passed	2 min 48 sec	Existing passed
idc-jenkins-ci-tidb/plugin-test	🟢 build success, plugin test success	4min	Existing passed