Regroup autogrouped notifications into app group on summary is posted

 When posting a group summary, find any ungrouped or force-grouped notifications from that group:
  - remove them from the ungrouped list or autogroup
  - regroup them into the app-provided group

Flag: EXEMPT bug fix
Test: atest GroupHelperTest

Bug: 408388738

Change-Id: I0b15bc6f86dd1aefe71c96ca71fe5e6ff1d3d6ac