ticdc/alert: add no owner alert rule (#3809)

[ti-chi-bot]

This is an automated cherry-pick of #3809

What problem does this PR solve?

TiCDC cluster could suffer no owner existence in some bug scenarios. Use threshold 0.5 because the metric update could have deviation. Close #4054

What is changed and how it works?

Add an alert rule to detect no owner for more than 10 minutes.

Check List

Tests

• Manual test (add detailed scripts or steps below)
  • test the rule manually

Release note

Add an alert rule when ticdc has no owner for more than 10 minutes.

[ti-chi-bot]

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[amyangfei]

/merge

[ti-chi-bot]

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

Commit hash: f3a54ab