Partial Revert of subId changes in ImsManager

Waiting for the subId of ImsManager to match the
remote MmTelFeature is too slow and is exposing
many race conditions with the vendor ImsServices
which expect IMS configurations to be available
when they receive CARRIER_CONFIG_CHANGED and not
once the IMS service loads the new configuration.

Bug: 217748245
Test: atest ImsCommonTests CtsTelephonyTestCases
Change-Id: I56e9f1134893940125fb381172238e177b618a5a