Fix incorrect call radio type on UI during silent redial

When handover takes place, the ImsPhoneConnection objects
attached to the handover call are not cleaned up until the call
ends on the CS pipe after handover. As a result, the stale object
keeps updating UI on the IMS registration state. This causes the
call UI to show WiFi call when the call is on CS. The fix here is
to clean up the ImsPhoneConnection objects as soon as they are
mapped to CS connections upon handover.

Bug: 29551456
Change-Id: Iafa668c29c9501d6c3845327a9b19458dbfdd84e