executor: skip merging global stats if the partitioned table cannot be found (#42462)

[ti-chi-bot]

This is an automated cherry-pick of #42462

What problem does this PR solve?

Issue Number: close #42007

Problem Summary:

What is changed and how it works?

When merging global stats, first check whether the partitioned table still exists. If not(the table may be dropped when analyzing partitions), skip merging global stats for the table.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

Add sleep into analyze code so we have time to drop table during the analyze period. Test that dropping the table during the period of both manual analyze and auto analyze would not cause panic.

• 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

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

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[ti-chi-bot]

@ti-chi-bot: This cherry pick PR is for a release branch and has not yet been approved by release team.
Adding the do-not-merge/cherry-pick-not-approved label.

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