Preventing the flaky fail from wallpaper condition mismatch.

The wallpaper show/hide is not synchrnoize with activity's window state,
add a show/hide waiting condition for the wallpaper state.
Remove some computeState to speed up the test.

Bug: 209906849
Test: run "atest KeyguardTests" for both legacy and shell-transition
Change-Id: I13241eb37a78b27d73875ff339e0552f8f4dc564
2 files changed