Prune and update OS list/install steps

Removed a bunch of old Debian, Ubuntu RHEL, and Fedora versions.

Link: <https://docs.fedoraproject.org/en-US/releases/>
Link: <https://en.wikipedia.org/wiki/Debian_version_history>
Link: <https://wiki.ubuntu.com/Releases>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>