update precision of DATETIME and TIMESTAMP values

[qiancai]

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What is changed, added or deleted? (Required)

Fix the precision of DATETIME and TIMESTAMP values from milliseconds to microseconds.

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For details, see tips for choosing the affected versions (in Chinese).

• master (the latest development version)
• v7.2 (TiDB 7.2 versions)
• v7.1 (TiDB 7.1 versions)
• v7.0 (TiDB 7.0 versions)
• v6.6 (TiDB 6.6 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)
• v5.2 (TiDB 5.2 versions)
• v5.1 (TiDB 5.1 versions)
• v5.0 (TiDB 5.0 versions)

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[ti-chi-bot]

[REVIEW NOTIFICATION]

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• Oreoxmt

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[dulao5]

👍

[Oreoxmt]

LGTM

[Oreoxmt]

LGTM

[guangleibao]

LGTM

[qiancai]

/remove-status LGT1
/status LGT4
/merge

[ti-chi-bot]

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

Commit hash: 4766b4b

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #13970.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.6: #13971.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.0: #13972.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.1: #13973.