Do not apply safe region letterboxing to test activity

- Since the TestActivity may no longer be full screen if safe region bounds are applied, the expected display hash will not be the expected one.
- The display hash received when a safe region letterbox is applied is non null but not the expected value.
- The safe region behavior can be verified in other tests in the class.

Bug: 404915525
Test: atest CtsWindowManagerDeviceDisplay
Flag: EXEMPT (bug fix)
Change-Id: I1dd058b6e474f720d4518ab993f9124dfb498eb0
1 file changed