Fix the CanForwardToProfileIdMap building logic

Change to only use the the first user in UserManagerState#getUserIds if
the current user is excluded. Otherwise, the current user should be used
to build the canForwardToProfileMap.

Bug: 429525969
Test: manual (steps mentioned in the bug) - http://shortn/_w342HHN1vO

Flag: android.multiuser.enable_moving_content_into_private_space

Change-Id: I9a17b9a8d3f90de99a90e15493ac96cae187b464