[SettingsLib] Remove access to isImsRegistered() and isActiveSubId()

1. Replace SubscriptionManager#isActiveSubId(int) into
   SubscriptionManager#isActiveSubscriptionId(int)
2. Replace TelephonyManager#isImsRegistered() into
   ImsMmTelManager#getRegistrationState()

Bug: 147534443
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=DataUsageSummaryTest
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=DataUsageUtilsTest
Change-Id: Ife93ad4a7dbd9d4c5d38a532e01cac19bb9e5fee