Joint2D and Joint: make set_exclude_nodes_from_collision respect signals

scene/2d/joints_2d.cpp

@@ -198,7 +198,9 @@ void Joint2D::set_exclude_nodes_from_collision(bool p_enable) {
 	if (exclude_from_collision == p_enable) {
 		return;
 	}
-
+	if (joint.is_valid()) {
+		_disconnect_signals();
+	}
 	_update_joint(true);
 	exclude_from_collision = p_enable;
 	_update_joint();

scene/3d/physics_joint.cpp

@@ -197,6 +197,10 @@ void Joint::set_exclude_nodes_from_collision(bool p_enable) {
 	if (exclude_from_collision == p_enable) {
 		return;
 	}
+	if (joint.is_valid()) {
+		_disconnect_signals();
+	}
+	_update_joint(true);
 	exclude_from_collision = p_enable;
 	_update_joint();
 }