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

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

Change-Id: Ib416aa8387f7700174bd71018adcbb10172f52c9