Update DeviceConfigService to call DeviceConfig API directly for get,
set, and reset. Remove the duplicated content uris from various places
in favor of the single constant exposed in DeviceConfig.
Test: atest FrameworksCoreTests:DeviceConfigTest
atest FrameworksCoreTests:SettingsProviderTest
atest SettingsProviderTest:DeviceConfigServiceTest
Bug:109919982
Bug:113100523
Bug:113101834
Change-Id: I46d110c4fd29a89af383629d26de4ee39ca852a6
1278d1c736