Fix exception handling in getState() binder cache

Bug: 153103051

A binder cache query function cannot compute a result based on any data
that is not known to the binder server.  If the code depends on local
data that can change, then invalidation will not work properly.

The getState() method returns OFF if the bluetooth service is
unavailable.  This computation now occurs in the getState() method,
outside of the binder cache query() method.

The query method converts RemoteExceptions to RuntimeExceptions.  Then,
the conversion is reversed in getState().  This double conversion is
needed because the cache query() method has no throw spec.

Test: Run 'atest BluetoothInstrumentationTests' with a special debug
image that enables binder cache VERIFY.  The test found no cache
inconsistencies.

Change-Id: I80db86f66d8b51fa94207824c8b15972a9066ef5