[wm]: System ui visibility policy for freeform windowing

Even though fullscreen app is using fullscreen system ui
visibility flag, status bar is showing when focus on freeform.

do not apply system ui visibility of freeform window.

Test: Manual - Watch status bar visibility whlie focus
Test: atest WmTests:DisplayPolicyTests, DisplayPolicyLayoutTests
Bug: 129509931
Change-Id: I6f3b1aedc9986fe38c5a3e8cb63266e711be9c9e
(cherry picked from commit a80b14dacb9037f804e7925f792886f992ec58dc)