For each remote cluster the auto follow coordinator, starts an auto
follower that checks the remote cluster state and determines whether an
index needs to be auto followed. The time since last auto follow is
reported per remote cluster and gives insight whether the auto follow
process is alive.
Relates to #33007
Originates from #35895
This commit fixes two issues with the CCR API specification:
- remove the CCR stats endpoint, it is not currently implemented
- fix the documentation links