Prune and update OS list/install steps

Removed a bunch of old Debian, Ubuntu, RHEL, and Fedora versions and add
some new ones.

There are newer releases of Fedora and Ubuntu, but we don't have
packages yet (next release maybe).

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>

Author: ac000