As kuryrnetpolicy CRD objects are namespaced, when a namespace is
deleted, the object is deleted by kubernetes as part of the namespace
deletion process. This was making network policy driver failing on
releasing the network policy as it could not find the object. This
patch ensures kuryr-controller doesn't fail in case kubernetes has
already deleted the kuryrnetpolicy object by skipping the exception
when trying to delete an already deleted object.
Closes-Bug: 1816020
Change-Id: I0443b65e5d6897c5d6673c222fc50101c244cd1e