Merge "Revert "Move IMS to a listener type model instead of a poll model"" am: 0ad2adeb48 am: ff98cd706b am: 36097789ba am: a5833e3316

Original change: https://android-review.googlesource.com/c/platform/packages/services/Telephony/+/1443077

Change-Id: I855f28c4f808424754b4f89c82b7150f12075bdf