[automerge] Waiting for snapshot layer gone for quick switch tests. 2p: 3402a4930e 2p: 22288c00e5

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17397263

Bug: 226684870
Change-Id: Ibff28748674e8c76628a63906feaa4f3b4621b1e