ddl: fix the issue about create columns with wrong default when sql_mode is empty.

[zimulala]

What problem does this PR solve?

Issue Number: close https://github.com/pingcap/tidb/issues/52972, close https://github.com/pingcap/tidb/issues/51320

Problem Summary:

What changed and how does it work?

Check List

Tests

• [x] 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

[tiprow[bot]]

Hi @zimulala. Thanks for your PR.

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 55.7545%. Comparing base (1d698c7) to head (800b0b0). Report is 12 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #52988         +/-   ##
=================================================
- Coverage   72.3811%   55.7545%   -16.6266%     
=================================================
  Files          1482       1597        +115     
  Lines        428743     600172     +171429     
=================================================
+ Hits         310329     334623      +24294     
- Misses        99115     242466     +143351     
- Partials      19299      23083       +3784     

Flag	Coverage Δ
integration	37.1662% <85.7142%> (?)
unit	71.2434% <100.0000%> (+0.0249%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9957% <ø> (ø)
parser	∅ <ø> (∅)
br	49.2175% <ø> (+8.0736%)	:arrow_up:

[zimulala]

/retest

[tiprow[bot]]

@zimulala: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/retest

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[ti-chi-bot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Defined2014, tangenta

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Needs approval from an approver in each of these files:

• ~~OWNERS~~ [Defined2014,tangenta]
• ~~pkg/ddl/OWNERS~~ [tangenta]

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[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2024-04-30 02:37:33.103366475 +0000 UTC m=+324806.860502042: :ballot_box_with_check: agreed by Defined2014.
• 2024-04-30 06:26:19.64581038 +0000 UTC m=+338533.402945950: :ballot_box_with_check: agreed by tangenta.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #53002.

[lance6716]

/cherry-pick release-6.5

[ti-chi-bot]

@lance6716: new pull request created to branch release-6.5: #53736.

In response to this:

/cherry-pick release-6.5

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