Update mysql Docker tag to v8.4.9 (#28139)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| mysql | patch | `8.4.5` → `8.4.9` |

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### Configuration

📅 **Schedule**: (in timezone Etc/UTC)

- Branch creation
  - Only on Sunday and Saturday (`* * * * 0,6`)
  - Between 12:00 AM and 12:59 PM, only on Monday (`* 0-12 * * 1`)
- Between 09:00 PM and 11:59 PM, Monday through Friday (`* 21-23 * *
1-5`)
- Between 12:00 AM and 04:59 AM, Tuesday through Saturday (`* 0-4 * *
2-6`)
- Automerge
  - Only on Sunday and Saturday (`* * * * 0,6`)
  - Between 12:00 AM and 12:59 PM, only on Monday (`* 0-12 * * 1`)
- Between 10:00 PM and 11:59 PM, Monday through Friday (`* 22-23 * *
1-5`)
- Between 12:00 AM and 04:59 AM, Tuesday through Saturday (`* 0-4 * *
2-6`)

🚦 **Automerge**: Enabled.

♻ **Rebasing**: Whenever PR is behind base branch, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update
again.

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