Try to fix the scrolling issue in AE flicker test

Previous, we scroll until it can no longer be scroll, which sometimes
brings up overview instead.

Now, change to scroll until find view.

Fix: 401265425
Test: atest FlickerTestsActivityEmbedding:OpenTrampolineActivityTest
Flag: EXEMPT test fix
Change-Id: I070d5ee672b4445758f892a92d0af19a452ae087