Root cause: Only using and querying the dialer intent can't be represented for supporting RTT. Next action: Add one checker for carrier config. Bug: 159242323 Test: manual test for AT&T, Google Fi, chunghwa sim & make RunSettingsRoboTests ROBOTEST_FILTER=RTTSettingPreferenceControllerTest Change-Id: I8e85b9fdfc658ea6855a4041691efdbfd07c62d6