ddl, tests: add expression default values feature relevant tests for some DDLs and fix a related bug (#51571)

[ti-chi-bot]

This is an automated cherry-pick of #51571

What problem does this PR solve?

Issue Number: close #51554, close #51570

Problem Summary:

What changed and how does it work?

• Add expression default values feature relevant tests for "modify column", "set/drop default" and "add index"
• When the default value is an expression, changing it to a constant by "set default" can be problematic

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (release-7.5@08ee45d). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.5     #53394   +/-   ##
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  Coverage               ?   72.0006%           
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  Files                  ?       1411           
  Lines                  ?     409913           
  Branches               ?          0           
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  Hits                   ?     295140           
  Misses                 ?      94909           
  Partials               ?      19864           

Flag	Coverage Δ
unit	72.0006% <100.0000%> (?)

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

Components	Coverage Δ
dumpling	53.9913% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	53.4639% <0.0000%> (?)

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [Defined2014,tangenta]
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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-05-21 02:43:45.972842999 +0000 UTC m=+2139579.729978564: ☑️ agreed by Defined2014.
• 2024-05-21 03:19:21.423692436 +0000 UTC m=+2141715.180828010: ☑️ agreed by tangenta.