Remove geo suggestion clearing

Remove strategy clearing / ignoring geo suggestions within
TimeZoneDetectorStrategyImpl when geo detection is disabled / the user
is changed.

The LocationTimeZoneManager's ControllerImpl withdraws suggestions in
these situations anyway. Removing the duplicated functionality from the
strategy helps avoid races (i.e. if the TimeZoneDetectorStrategy and
LocationTimeZoneManager receive the same "something has changed" signal
in an ill-defined order it could lead to suggestions being "missed").
This should open up opportunities for future droidfood testing
(i.e. the ability to run geo detection "in the background" and record /
report them in metrics during QA, bug 200279201).

Test: atest services/tests/servicestests/src/com/android/server/timezonedetector/
Test: atest cts/hostsidetests/time/host/src/android/time/cts/host/
Bug: 200279201
Bug: 197624972
Change-Id: I2e5ea8482216ef204cf2e7ad412eeb0f501e36b9