Ensure ProxCheck doesn't unregister ProxSensor

If the ProximitySensor passed into ProximityCheck is shared with other
clients, the ProximityCheck was causing the ProximitySensor to be
paused which, in turn, meant other clients would miss out on events.

Specifically, this manifested itself in AOD/Doze where one part of
Doze wanted the proximity sensor registered, but another part used
ProximityCheck with the same sensor, causing the sensor to be
paused. The screen would either not turn off when covered, or would
not turn back on when uncovered.

This CL is a cherry pick of an earlier CL that went into rvc-d1.
Some slight differences are seen since the proximity code in rvc-d1
has diverged from rvc, but the logic needed for the fix is the same.

Fixes: 155365422
Test: atest SystemUITests and manual
Change-Id: I3c3faf79ba6d3915b0cfecec7861f6065ae689e8
Merged-In: I3c3faf79ba6d3915b0cfecec7861f6065ae689e8