Bypass openvswitch update logic if expected packages are not present
The nuage integration uses a different package name for openvswitch,
breaking the update steps. This patch bypasses the update logic if the
expected packages are not present allowing nuage deployments to manage
the openvswitch package some other other way.
Due to path restructuring and file renaming, this is a semantic
backport of https://review.opendev.org/#/c/702677/. This patch also
includes similar modifications in the update_tasks for layered
packaging on queens.