Make sure only stream leader does a republish

Signed-off-by: Derek Collison <derek@nats.io>

server/jetstream_cluster_test.go

@@ -10662,7 +10662,7 @@ func TestJetStreamClusterStreamRepublish(t *testing.T) {
 		Name:     "RP",
 		Storage:  MemoryStorage,
 		Subjects: []string{"foo", "bar", "baz"},
-		Replicas: 1,
+		Replicas: 3,
 		RePublish: &RePublish{
 			Source:      ">",
 			Destination: "RP.>",

server/stream.go

@@ -3569,7 +3569,7 @@ func (mset *stream) processJetStreamMsg(subject, reply string, hdr, msg []byte,
 			thdrsOnly = mset.cfg.RePublish.HeadersOnly
 		}
 	}
-	republish := tsubj != _EMPTY_
+	republish := tsubj != _EMPTY_ && isLeader
 
 	// We hold the lock to this point to make sure nothing gets between us since we check for pre-conditions.
 	// Currently can not hold while calling store b/c we have inline storage update calls that may need the lock.