"Run in background" less aggressively

"Run location time zone detection algorithm in background" less
aggressively.

In a recent bug affecting a teamfooder, they were expecting that
toggling auto tz would force the time zone detector to forget previous
suggestions. Because "run in background" was enabled, this didn't have
the result they expected as the location-based time zone detection
algorithm just kept running. We get to define/change what this internal
testing flag does and it's not widely used and behavior is arbitrary so
this commit changes that behavior.

Testing:
$ adb shell cmd device_config put system_time location_time_zone_detection_run_in_background_enabled true
$ adb shell dumpsys time_zone_detector
<Toggle auto tz>
$ adb shell dumpsys time_zone_detector

...before and after.

Bug: 267788915
Test: Manual testing described above + treehugger
Test: atest services/tests/servicestests/src/com/android/server/timezonedetector/ConfigurationInternalTest.java
Test: atest services/tests/servicestests/src/com/android/server/timezonedetector/location/LocationTimeZoneProviderControllerTest.java
Change-Id: I2b2700b61f7977beb93a6060708cc34763e2b0a5