A mixed bag of tidy ups / refactoring

A mixed bag of tidy ups / refactoring to make the following commits
smaller. This change is not intended to have any user-facing functional
impact.

Summary of changes that aren't obvious comment / code / string tidy-ups:

1) Support for geolocation time zone detection support configuration via
the system property
"persist.sys.location_time_zone_detection_feature_supported" has been
removed. I haven't used this recently and "real" devices get to use
server flags to turn the feature off now. Turning the feature on will
have to be done in .xml config after this.

2) Remove Dumpable.Container from TimeZoneDetectorInternal and
TimeZoneDetectorStrategy as it is not used.

3) Add support for adding Dumpable to TimeZoneDetectorService, because
it will be used in a following commit. Removed Dumpable.Container
interface as it's not currently pulling its weight, with only one user
where nothing refers to the interface.

4) Put all debugging logging under control of a constant in
TimeZoneDetectorService.

Bug: 197624972
Test: treehugger
Test: atest services/tests/servicestests/src/com/android/server/timezonedetector/
Change-Id: I3c3895b3ec7b0ad88fc3776221616a973d54863b