Improve the activity coalescing

- 2 Activities shouldn't coalesce if they have different launch bounds.
- Launch bounds can be different when activities are started in task
  views.
- When host app triggers start command for multiple activities at the
  same time, sometimes these activities coalesce into each other
  leading to an inconsistent task view state.

Fix: 274155443
Test: Tested manually on gcar-ui-portrait
Change-Id: Ib083da2d5500c81b07885630d08767d512076b66