Making it clear that a test sees the keyguard for the first time.

This help to find a test which bugreport may still contain a recent crash in SysUI. This is the tests that prints "for the first time = true"

Test: presubmit
Bug: 187761685
Change-Id: Ic24a1d6f4ba36e117df2166c57bbc0a1d021cc7d