planner: fix inconsistent schema between UnionAll and child operator (#30231)

[ti-srebot]

cherry-pick #30231 to release-5.0
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/30838

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---

What problem does this PR solve?

Issue Number: close #29705

Problem Summary:

The schema of the UnionAll is different from its children operators. Then the Union Exec returns an error.

In this case, the UnionAll has one column but its child Aggregation has two. It's caused by an extra column is added to Aggregation in (*LogicalAggregation).PruneColumns().

What is changed and how it works?

Add extra logic in (*LogicalUnionAll).PruneColumns to handle this case.
When UnionAll finds its child has more columns, it will add the extra Projection to prune the extra column.

About the additional changes in the test, please see the issue.

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:

• lcwangchao
• winoros

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[ti-srebot]

/run-all-tests

[ti-srebot]

@time-and-fate you're already a collaborator in bot's repo.

[time-and-fate]

/merge

[ti-chi-bot]

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

Commit hash: d2c6c5b

[XuHuaiyu]

/merge

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[XuHuaiyu]

/merge