changefeedccl: automatically replan changefeeds

Changefeeds can start to exhibit poor behavior as replicas change the location of the watched data over time. We could do something like the [DR team did and deploy a side car](https://github.com/cockroachdb/cockroach/blob/563369567e594c4bd545ca23e0f2f9c2505fc6a0/pkg/sql/distsql_plan_bulk.go#L212) that monitors potential changes to the plan over time and triggers the changefeed to replan under certain conditions.

Jira issue: CRDB-38817

Start by reading the referenced sidecar implementation in pkg/sql/distsql_plan_bulk.go, especially around the linked line, and then trace how changefeeds construct and maintain their plans. Clarify which replica or plan changes should trigger replanning and how those conditions can be tested. Done means changefeeds automatically replan under agreed conditions without disrupting normal operation.

Written by the indexing model from the issue text.