Don't suppress group change after summary removed

Fixes: 226122072
Test: atest ShadeListBuilderTest
Test: 1. Post a group w/ 2 children in Notify.apk
      2. Inline reply 1 child
      3. Dismiss other child
      Observe: First child still present in shade.
Change-Id: If9e9991c34ae7871ceced7d9606a75d060110209