Blender Git Loki

Fix T74492: Reset Face Set data when cancelling the expand operator

The operator was resetting the mask data when cancelling instead of the
face set data, so it was crashing because mask data was not available
when starting the operator in expand face set mode.

Reviewed By: brecht

Maniphest Tasks: T74492

Differential Revision: https://developer.blender.org/D7043