.github: delete stale workflow

[ran-huang]

Signed-off-by: Ran huangran@pingcap.com

What is changed, added or deleted? (Required)

Delete the Stale GitHub Action because we use Ti Chi for issue lifecycle management now.

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

• master (the latest development version)
• v5.0 (TiDB 5.0 versions)
• v4.0 (TiDB 4.0 versions)
• v3.1 (TiDB 3.1 versions)
• v3.0 (TiDB 3.0 versions)
• v2.1 (TiDB 2.1 versions)

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

• This PR is translated from: .github: delete stale workflow docs-cn#5731
• 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

[ran-huang]

/translation from-docs-cn
/cc CharLotteiu TomShawn

[CharLotteiu]

LGTM

[TomShawn]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• CharLotteiu
• TomShawn

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[ran-huang]

/merge

[ti-chi-bot]

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

Commit hash: 3b170ed