update precision of DATETIME and TIMESTAMP values

[qiancai]

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What is changed, added or deleted? (Required)

Which TiDB version(s) do your changes apply to? (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.

• 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)

What is the related PR or file link(s)?

• This PR is translated from: update precision of DATETIME and TIMESTAMP values docs-cn#13969
• Other reference link(s):

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• Oreoxmt

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[Oreoxmt]

LGTM

[guangleibao]

LGTM

[qiancai]

/remove-status LGT1
/status LGT2
/merge

[ti-chi-bot]

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

Commit hash: 2d66dfa

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.1: #13566.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #13567.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.6: #13568.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.0: #13569.