runtime: Ensure container gets cleaned up on shutdown
Recent refactoring to simplify the Runtime class inadvertantly removed the cleanup code. As a result, a container would not be stopped and removed when shrinkwrap exits but would linger, using system resources.
Fix that by reintroducing the cleanup code.
Fixes: 1db05f5a ("runtime: replace modal stack with singleton") Signed-off-by: Ryan Roberts ryan.roberts@arm.com