Normalizing the way tests invoke Recents

Avoiding pressing recent_apps button.
Waiting until Recents appears and system’s idle everywhere.

Tests are going to be broken until Launcher starts to respond to
pressRecentApps() call correctly.

Bug: 72967764
Test: atest google/perf/app-transition/app-transition-to-recents
Test: atest google/perf/jank/SystemUI/UbSystemUIJankTests:android.platform.systemui.tests.jank.SystemUiJankTests#testRecentAppsFling

Change-Id: I4f80c0ec6d055769d60874abde2280ea227e1fd1