rules: Migrate rules defined in docs to api/v2/rules endpoint

[rimadeodhar]

The api/v2/rules endpoint should be augmented with the alerting rules loosely defined in the docs section on CRDB alerting https://www.cockroachlabs.com/docs/stable/monitoring-and-alerting.html#events-to-alert-on. The api/v2/rules endpoint was created as a programmatic way to provide alerting and aggregation recommendations for our metric. For the sake of completeness, we should also include the existing set of alerts defined within our docs.

Jira issue: CRDB-13938

[mari-crl]

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[rail]

Manually synced with Jira