[Tetheirng] Refactor carrier config to EntitlementManager

- To reduce CarrierConfigManager access times, move CarrierManager
  to TetheringConfiguration.

Bug: 225900149
Test: atest EntitlementManagerTest pass
Test: atest TetheringConfigurationTest pass
Change-Id: I5b206e2bc012cbbca26fb1e5c72558383981f183
5 files changed