[wip]dist/ddl: add subtask metrics

[okJiang]

What problem does this PR solve?

Issue Number: close #47017

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 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

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[tiprow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
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