Fix flacky Private profile test due to wrong API usage

doesPrivateSpaceExist was using API which was returning profiles
including those which were disabled (marked for removal).

Bug: 384567451
Test: atest com.android.settings.privatespace.PrivateSpaceMaintainerTest#profileRemovedFromUserManager_privateSpaceNoLongerExists
Flag: EXEMPT bugfix
Change-Id: Id46ef613bf6e855963949c86361cf22714fd2b70