metrics: refine alert rules

[overvenus]

What problem does this PR solve?

• remove tikv_enabled_hibernate_regions.
• remove ticdc_puller_entry_sorter_merge_duration_time_more_than_2s.
• remove ticdc_puller_entry_sorter_sort_duration_time_more_than_2s.
• tikv_cdc_min_resolved_ts_no_change_for_1m alerts only when there
  are captured regions.
• extend allowed scan duration from 30s to 10min for
  tikv_cdc_scan_duration_seconds_more_than_10min

Close tikv/tikv#11017
Close https://github.com/pingcap/ticdc/issues/2156

Check List

Tests

• Manual test (add detailed scripts or steps below)

Tested manually,

1. Start cdc cluster
2. Create a changefeed
3. Pause the changefeed.
4. Wait 2 minutes.

Related changes

• Need to cherry-pick to the release branch
• Need to update key monitor metrics in both TiCDC document and official document

Release note

Fix tikv_cdc_min_resolved_ts_no_change_for_1m keep firing when there is no changefeed.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• amyangfei

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[overvenus]

/merge

[ti-chi-bot]

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

Commit hash: 72ae133

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #3023.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #3024.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #3025.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #3026.