Revert "Set overlayable for CarsystemUI NavBar"

This reverts commit 165bf8f44a5877d3e677cf21717f1d3f18e5354e.

Reason for revert: b/159143515

Test: build sdk_gcar_x86, nav bar overlay should work as usual
Bug: 159143515
Change-Id: I34e7a0925dd2fb243a11ddd46ac75fbcf3a92f3b
1 file changed