multi: add logs when subservers are starting

Also unified the log messages.

watchtower/wtclient/client.go

@@ -439,7 +439,7 @@ func (c *TowerClient) buildHighestCommitHeights() {
 func (c *TowerClient) Start() error {
 	var err error
 	c.started.Do(func() {
-		c.log.Infof("Starting watchtower client")
+		c.log.Infof("Watchtower client starting")
 
 		// First, restart a session queue for any sessions that have
 		// committed but unacked state updates. This ensures that these