*: Fixed double writing to correct hash/key partition during reorg

[mjonss]

What problem does this PR solve?

Issue Number: close #43892

Problem Summary:
The double writing during ADD/COALESCE PARTITION (for HASH/KEY partitioned tables) would use the old number of partitions, resulting in writing to the wrong partition, which may cause duplicate or lost rows.

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

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

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• TonsnakeLin
• bb7133

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[bb7133]

LGTM

[TonsnakeLin]

It's greate job to find this issue and fix it. LGTM.

[tiancaiamao]

/merge

[ti-chi-bot]

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

Commit hash: ebd2207

[Defined2014]

/retest

[hawkingrei]

/retest

[Defined2014]

/retest

[hawkingrei]

/retest

[hawkingrei]

/test all

[hawkingrei]

/retest

[mjonss]

/test check_dev_2

[ti-chi-bot]

@mjonss: The specified target(s) for /test were not found.
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[mjonss]

/test check-dev2

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #43970.