Fix few issues in virtual camera service:

  * Fix incorrect flush implementation (do not try to fetch element from
    empty queue).
  * Gracefully handle flush call even if render thread is not running.
  * Make sure thread is terminated when close is called on session.
  * Remove metadata from CaptureResult send when processing flush
    request.
  * Set streamId to -1 in ErrorRequest NotifyMsg (required, otherwise
    it NotifyMsg fails validation in framework).

Bug: 301023410
Test: atest virtual_camera_tests
Test: OpenCamera
Change-Id: I899a9eaed0b69eed93945391c2d0a25120136267
diff --git a/services/camera/virtualcamera/VirtualCameraSession.h b/services/camera/virtualcamera/VirtualCameraSession.h
index 6df5d58..50962e5 100644
--- a/services/camera/virtualcamera/VirtualCameraSession.h
+++ b/services/camera/virtualcamera/VirtualCameraSession.h
@@ -56,7 +56,7 @@
 
   virtual ~VirtualCameraSession() override = default;
 
-  ndk::ScopedAStatus close() override;
+  ndk::ScopedAStatus close() override EXCLUDES(mLock);
 
   ndk::ScopedAStatus configureStreams(
       const ::aidl::android::hardware::camera::device::StreamConfiguration&