[Settings] Replace isVolteEnabledByPlatform

Replace ImsManager#isVolteEnabledByPlatform() by ImsMmTelManager#isSupport().

Bug: 140542283
Test: m RunSettingsRoboTests -j ROBOTEST_FILTER=Enhanced4gBasePreferenceControllerTest
Test: m RunSettingsRoboTests -j ROBOTEST_FILTER=Enhanced4gLteSliceHelperTest
Change-Id: I656a00ad2c6120255e53d0b836945462258e01bb
6 files changed