Only inherit task bounds for new single tasks

Normal task launches use `FLAG_ACTIVITY_NEW_TASK` which can cause them
to be wrongly caught but the task trampoline bounds logic. Testing has
shown that a common signature of these task trampolines is to use single
task launches. Update task trampoline bounds heuristic to only apply to
single task launches.

Flag: com.android.window.flags.inherit_task_bounds_for_trampoline_task_launches
Test: atest WmTests:DesktopModeLaunchParamsModifierTests,
atest WMShellUnitTests:DesktopTasksControllerTest
Fixes: 401296527
Fixes: 403470140
Change-Id: I73492e5500b5023687a13403ef472016cb76aaa5