More app ops fg/bg tuning

- Only report that something has changed when a uid changes between
  the restricted and unrestricted states.  (Adds new constant that
  defines this important division point.)

- Have different settle times for different key transitions: (a)
  out of the top state, (b) out of any other unrestricted state,
  (c) down to a lower background state.

- But, don't apply any settle time when transitioning from top to
  another unrestricted state...  there is no need to.

Bug: 78480444
Test: manual
Change-Id: Ife772858009a6da5c286e285a4059aea3ad3f6c7