Remove unnecessary ranking calls

Some operations, such as no-op channel updates or setting delegates, do not affect notification ranking. Therefore re-running the signal extractors is a waste of time.

(Also remove the Delegate.mUserAllowed concept since it's unused).

Fixes: 272716546
Test: atest PreferencesHelperTest
Change-Id: I069dd30363fbdda7355794f2e20539b58728a2e6