UserProperty cross-binder warning only for SYSTEM

We currently warn when getUserProperties() is called where the
callingUid differs from the processUid. This is really only an
interesting situation when called from the SYSTEM (uid 1000), since
otherwise the binder call will equate the two anyway.

Since this is now of much lower frequency, we can log this warning for
regular devices too, not just eng builds.

Test: Manual. Just a logging change.
Flag: EXEMPT bugfix
Change-Id: I9be85c825549743ad281eedd6da550548d011642