kvserver: dump goroutines when raft scheduler stuck

Capture a goroutine profile when the raft scheduler stops doing work (despite presence of a raft queue). We can also simply do this in case the raft queue is at high cardinality (not necessarily high byte size, since that can happen due to overload).

See https://github.com/cockroachdb/cockroach/issues/159139

This is easier now because of https://github.com/cockroachdb/cockroach/issues/159342

Jira issue: CRDB-58760