packaging: Make Fedora spec file CentOS compatible

packaging: Make Fedora spec file CentOS compatible

On CentOS, the package names aren't prefixed with python2, but rather
are prefixed with simply python. This change addresses that and fixes
up some documentation that was outdated, and updates the Vagrantfile
to use the proper spec file and package names.

Fixes: bb1a7ca21107 ("fedora: Add python3-openvswitch split package")
Signed-off-by: Leif Madsen <lmadsen@redhat.com>
Signed-off-by: Russell Bryant <russell@ovn.org>