Replace LocaleTracker with CountryDetector

Because CountryDetector considers more sources than what LocaleTracker
considers to report country ISO and thus it might be more comprehensive,
use CountryDetector instead of LocaleTracker to update Country ISO for
EmergencyNumberTracker.

Test: Manual
Bug: 120849585
Change-Id: I731c39adc0493979fe4c12e99fd65507c8da4177
Merged-In: I731c39adc0493979fe4c12e99fd65507c8da4177
(cherry picked from commit fa0d8719)