Fix how displays are used in test cases am: 017cb98ee9 am: b536f21f4c am: f1ccb71825

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2305821

Change-Id: Ibddcf3a941ffa3cd306bd56cff2127e9df17dd5f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>