canAddMoreProfilesToUser considers MaxSupportedUsers

There was a slight bug in the previous code. Managed profiles were
subject to not exceeding maxSupportedUsers, but other profile types
evaded that condition. It should apply to all profile types (in fact,
all users except guest and demo).

Bug: 208842920
Test: treehugger
Change-Id: I104be8466193376b09e9f4d8c112eb947da7c9c4