Merge "Camera: Exit PreviewStreamSpacer when disconnecting stream" into tm-dev am: c3a3ee8362 am: 16f61fcb6e am: 62d0623c62 am: b011453ca4

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

Change-Id: Ia8f73ad0a0f0bf18f08b77b3b1596308a07c8fa8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>