Removing groups & ongoing from bubble ordering

* We don't allow ongoing bubbles so remove logic
* We were still grouping bubbles by app and this is
  something we're no longer supposed to do as per ux
  so removed this code

Bug: 155515999
Test: atest BubbleDataTest
Change-Id: I5de5dec6d8be70f638c0cc6121e859a51e44c563