Apply delivery group policies to CLOSE_SYSTEM_DIALOG broadcast.

- The "set-defer-until-active" policy is applied so that the
broadcast targeted to apps in the Cached state is deferred until
they come out of that state.
- The "deliver-most-recent" policy is applied so that if there are
already pending broadcasts waiting to be delivered when a new
broadcast is sent, the old ones are discarded.

Bug: 271950524
Test: TH
Change-Id: Id3bd218e9b54e93ca57607602730836fd12affc8