Mesh: Tag no loose vertices for Manifold Boolean output

Saves a tiny amount of time computing the loose vertices cache
after a boolean operation. Since the boolean output is just created
from faces, there are no loose vertices (there are also no loose
edges because of the call to `mesh_calc_edges`, which itself
tags the loose edge cache).

source/blender/geometry/intern/mesh_boolean_manifold.cc

@@ -714,7 +714,7 @@ static Array<Vector<int, face_group_inline>> get_face_groups(const MeshGL &mgl,
  * Return 1 if \a group is just the same as the original face \a face_index
  * in \a mesh.
  * Return 2 if it is the same but with the normal reversed.
- * Return 0 otherwise. 
+ * Return 0 otherwise.
   */
 static uchar check_original_face(const Vector<int, face_group_inline> &group,
                                  const MeshGL &mgl,
@@ -1606,6 +1606,10 @@ static Mesh *meshgl_to_mesh(MeshGL &mgl,
       get_intersecting_edges(r_intersecting_edges, mesh, out_to_in, mesh_offsets);
     }
   }
+
+  mesh->tag_loose_verts_none();
+  mesh->tag_overlapping_none();
+
   return mesh;
 }