Merge "Correct issue with auto disconnect conference where no participants." into sc-dev am: 01fb7193e5 am: 33b0e8d6fd

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/services/Telephony/+/14905269

Change-Id: Iaf48ae13b469503af8d7c0bf6c568fd9920da792