Add UserManagerInternal#getProfileIds()

The public API

  int[] UserManager#getProfileIds(int userId, boolean enabledOnly)

looks to be used enough in system_server process.  Let's have it in
UserManagerInternal as well.

Bug: 234882948
Test: atest CtsInputMethodServiceHostTestCases:MultiUserTest
Change-Id: Ie1e6bab0f9a5d2801ad57c89c23f0798276d8aa2