Portals - fix DYNAMIC particle systems

A regression had occurred whereby particle systems in DYNAMIC mode weren't added to the room correctly.
This PR recognise the case and bypasses the function to retrieve geometry, as retrieving the geometry is not necessary for DYNAMIC objects as they should not affect the room bound. Their AABB will be retrieved during gameplay rather than once off at level conversion.

(cherry picked from commit d86061d7ae167c3811009d334c6028a6521cd71b)

scene/3d/room_manager.cpp

@@ -1281,13 +1281,17 @@ void RoomManager::_process_static(Room *p_room, Spatial *p_node, Vector<Vector3>
 	bool ignore = false;
 	VisualInstance *vi = Object::cast_to<VisualInstance>(p_node);
 
+	bool is_dynamic = false;
+
 	// we are only interested in VIs with static or dynamic mode
 	if (vi) {
 		switch (vi->get_portal_mode()) {
 			default: {
 				ignore = true;
 			} break;
-			case CullInstance::PORTAL_MODE_DYNAMIC:
+			case CullInstance::PORTAL_MODE_DYNAMIC: {
+				is_dynamic = true;
+			} break;
 			case CullInstance::PORTAL_MODE_STATIC:
 				break;
 		}
@@ -1335,7 +1339,7 @@ void RoomManager::_process_static(Room *p_room, Spatial *p_node, Vector<Vector3>
 					// NOTE the is_visible check MAY cause problems if conversion run on nodes that
 					// aren't properly in the tree. It can optionally be removed. Certainly calling is_visible_in_tree
 					// DID cause problems.
-					if (mi->get_include_in_bound() && mi->is_visible()) {
+					if (!is_dynamic && mi->get_include_in_bound() && mi->is_visible()) {
 						r_room_pts.append_array(object_pts);
 					}
 
@@ -1353,12 +1357,13 @@ void RoomManager::_process_static(Room *p_room, Spatial *p_node, Vector<Vector3>
 				AABB aabb;
 
 				// attempt to recognise this GeometryInstance and read back the geometry
-				if (_bound_findpoints_geom_instance(gi, object_pts, aabb)) {
+				// Note: never attempt to add dynamics to the room aabb
+				if (is_dynamic || _bound_findpoints_geom_instance(gi, object_pts, aabb)) {
 					// need to keep track of room bound
 					// NOTE the is_visible check MAY cause problems if conversion run on nodes that
 					// aren't properly in the tree. It can optionally be removed. Certainly calling is_visible_in_tree
 					// DID cause problems.
-					if (gi->get_include_in_bound() && gi->is_visible()) {
+					if (!is_dynamic && gi->get_include_in_bound() && gi->is_visible()) {
 						r_room_pts.append_array(object_pts);
 					}