RESTRICT AUTOMERGE Clear the BAL allowlist duration

Clearing BAL privileges of a PendingIntent only cleared the tokens,
but kept the duration based entries. `clearAllowBgActivityStarts` is exclusively used by SystemUI (in NotificationManagerService) and fixing this is part of fixing a security vulnerability (therefore and because this is a low risk change it is not flag guarded).

BYPASS_INCLUSIVE_LANGUAGE_REASON=Using an existing API

Bug: 322159724
Flag: EXEMPT bugfix
Test: atest PendingIntentControllerTest
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:5782703d0f7c913477f1dd59b11e6e6e879199d9)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:014d574afb413850c300f07af43148bf8ff684b6)
Merged-In: I88e4df8fe4989fbc26aaa0e672626f3a1042678e
Change-Id: I88e4df8fe4989fbc26aaa0e672626f3a1042678e