ddl: fix issue of alter last partition failed when partition column is datetime (#48815)

[ti-chi-bot]

This is an automated cherry-pick of #48815

What problem does this PR solve?

Issue Number: close #48814

Problem Summary: fix issue of alter last partition failed when partition column is datetime

What changed and how does it work?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

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

[crazycs520]

/retest-required

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-11-27 04:21:29.478535579 +0000 UTC m=+810118.143761774: ☑️ agreed by tiancaiamao.
• 2023-11-27 04:21:43.033315788 +0000 UTC m=+810131.698541982: ☑️ agreed by wjhuang2016.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mjonss, tiancaiamao, wjhuang2016

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• pkg/ddl/OWNERS [wjhuang2016]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[crazycs520]

/merge

[ti-chi-bot]

@crazycs520: We have migrated to builtin LGTM and approve plugins for reviewing.

Please use /approve when you want approve this pull request.

The changes announcement: LGTM plugin changes

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.