Previously, attribute propagation did not work correctly in when only deleting edges and faces (but not points). Face and face corner attributes were propagated wrongly or not at all respectively. In order to keep the patch relatively small for the release branch, it does not include some small optimizations. These can be done in 3.1: * Use a `Span<int>` instead of `IndexMask` to avoid creating an unnecessary `Vector<int64_t>`. * Only prepare index mappings when there are actually attributes to propagate. Differential Revision: https://developer.blender.org/D13338