Don't set freeform bounds for fullscreen task on desktop enabled devices

The legacy freeform mode applied freeform bounds to fullscreen task so
that the defualt freeform bounds can easily be restored later. However,
for devices which support and have desktop mode enabled, storing these
freeform bounds for fullscreen tasks is not needed and thus can be
omitted.

Flag: NONE Exempt
Test: atest WmTests:TaskLaunchParamsModifierTests
Bug: 421055142
Change-Id: I22f07ca8462a2cc28c2f29fe199c04afe1b8acaf