Frameworks: Annotate trivial @GuardedBy in services/autofill

Add @GuardedBy for simple functions that require a single lock
and are named XYZLocked.

Derived by errorprone.

Bug: 73000847
Test: m
Test: m javac-check-framework RUN_ERROR_PRONE=true
Change-Id: I76889beb0a992dbd3e638e224111749814d2fe7b