In this commit we just pass a fencing_token
through hint_mutation RPC verb.
The hints manager uses either
storage_proxy::send_hint_to_all_replicas or
storage_proxy::send_hint_to_endpoint to send a hint.
Both methods capture the current erm and use the
corresponding fencing token from it in the
mutation or hint_mutation RPC verb. If these
verbs are fenced out, the server stale_topology_exception
is translated to a mutation_write_failure_exception
on the client with an appropriate error message.
The hint manager will attempt to resend the failed
hint from the commitlog segment after a delay.
However, if delivery is unsuccessful, the hint will
be discarded after gc_grace_seconds.
Closes#14580