sql: fix error in tidb_ddl_job

[hfxsd]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-09-30 09:18:53.945829146 +0000 UTC m=+260089.366042159: ☑️ agreed by qiancai.

[hfxsd]

/approve

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #18731.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #18732.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #18733.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.2: #18734.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.3: #18735.