Neutorn uses oslo.cache library for caching. This change ensures that
options of the library are included in neutron.conf generated by
oslo-config-generator.
This change also removes cache_utils module from neutron.opts because
the module is not used in that file.
Closes-Bug: #1940790
Change-Id: I9ccd145d5ea1a1e0033eb43b609cc6428ea95f23