Merge "Camera: Exit PreviewStreamSpacer when disconnecting stream" into tm-dev am: c3a3ee8362

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/18415584

Change-Id: I46884889b115942a5441fa69e280ed31e49d98de
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>