deprecate RawNode.TickQuiesced()

`TickQuiesced()` was originally added for use with range quiescence in
CockroachDB, but hasn't been in use since 2018. This patch marks it as
deprecated, to be removed in a future release.

Signed-off-by: Erik Grinaker <grinaker@cockroachlabs.com>

rawnode.go

@@ -72,6 +72,8 @@ func (rn *RawNode) Tick() {
 //
 // WARNING: Be very careful about using this method as it subverts the Raft
 // state machine. You should probably be using Tick instead.
+//
+// DEPRECATED: This method will be removed in a future release.
 func (rn *RawNode) TickQuiesced() {
 	rn.raft.electionElapsed++
 }