ExternalCameraHAL: fix CTS failures with callback for errors

For every request, either requestStreamBuffers fails or
handling of the requested buffer fails, always trigger
the processCaptureResult callback by notifying the request
is ready. This avoids the errors like the service side
receives fewer results than the requests and waits until
timeout.

Bug: 299182874
Test: cts
cts-tradefed run cts \
  --include-filter  "CtsCameraTestCases android.hardware.camera2.cts.RobustnessTest" \
  --include-filter "CtsCameraTestCases android.hardware.camera2.cts.PerformanceTest" \
  --include-filter "CtsCameraTestCases android.hardware.camera2.cts.StillCaptureTest" \
  --include-filter "CtsCameraTestCases android.hardware.camera2.cts.SurfaceViewPreviewTest" \
  --include-filter "CtsCameraTestCases android.hardware.cts.CameraGLTest" \
  --include-filter "CtsCameraTestCases android.hardware.cts.LegacyCameraPerformanceTest" \

Change-Id: I86ba422524e79af6b318b50bd6eebe2cb27fa50a