Ignore Keyguard-specific tests on VR headsets

On VR headsets, there is no keyguard. Skip tests that involve going to
the keyguard (but not tests that set a lock screen).

Bug: 64527423
Test: Verify the tests are skipped when the UI mode is locked to
UI_MODE_TYPE_VR_HEADSET

Change-Id: I0b41cd6759300d504e5cc4d7c6ef9d5746797d48
3 files changed