Fix default app size for desktop proto 2

Make sure tasks launch in the default size for the prototype. And that
it does not use the default phone size.
In proto 2, we don't set the tasks to freeform at this stage yet. But
the task bounds do not take effect in fullscreen tasks. Use the desktop
mode bounds for all standard activity type tasks.

Bug: 269661358
Test: atest DesktopModeLaunchParamsModifierTests

Change-Id: I424dec21fb295300aefa6f74ee4ca70401529f69