*: Remove old syntax ALTER TABLE ... ADD/REMOVE/ALTER PLACEMENT POLICY ...

[lcwangchao]

What problem does this PR solve?

Issue Number: close #29602

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

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• morgo
• xhebox

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[lcwangchao]

/run-all-tests

[morgo]

/merge

[ti-chi-bot]

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

Commit hash: f3981e8

[ti-chi-bot]

@lcwangchao: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[AilinKid]

lgtm