Fixing test failure in CtsCameraHeadlessSystemUserTestCases.

Using DeviceState JUnitRule to enforce the precondition RequireHeadlessSystemUserMode so that these tests are only run
when device supports Headless System User Mode.

Bug:305902403
Test: Run test Camera2HeadlessSystemUserTest#testHeadlessSystemUser_InvalidAccess[1]
for lunch target aosp_cf_x86_64_only_phone-trunk_staging-userdebug.

Change-Id: Iddc7001d89a0c49aa9c380f337890938415d2f42
1 file changed