Prevent minimized state changing from other transitions.

Prevent minimized state changing from other transitions.

- When calling adjustFocusedActivityStackLocked(), prevent the home stack
  from being brought forward if the task is not over the home stack.  This
  was causing issues with the docked stack triggering minimized mode when
  a task was removed in the assistant stack.
- When checking the visibility of the docked stack, only base it on the
  visibility of the assistant stack when it is above the docked stack.
  This was causing issues with the docked stack reporting as visible even
  when behind the assistant stack due to the subsequent code being run.

Bug: 35363819
Test: android.server.cts.ActivityManagerAssistantStackTests
Change-Id: I48cc901cb6b6166697a4130cc4639ee8f9581f02