Check for multi-window mode in AppTaskTests and ActivityManagerTest. Some form factors may force tasks into multi-window mode and previous activities may remain visible in that case. Fix: 350087414 Bug: 350079583 Test: AppTaskTests ActivityManagerTest Flag: TEST_ONLY (cherry picked from https://android-review.googlesource.com/q/commit:eb6ceba5bc3fc894fbcba52ea3989e4aa79f447d) Merged-In: I8fa2aaa0af34665a9c9c1f59b2f3aa70c69a6bfc Change-Id: I8fa2aaa0af34665a9c9c1f59b2f3aa70c69a6bfc