Make historical op getters async for real

The system server side was doing the work async and the binder call
was not oneway resulting in sync behavior for APIs desinged to be
async.

bug:147435904

Test: atest android.app.appops.cts.HistoricalAppopsTest

Change-Id: Ib184302798b58934ba9a0617a6a407f3aaa469af