Ref T13658. This just scrubs some of the simple references from the codebase.
Most of what's left is in documentation which won't be relevant for a fork and/or which I need to separately revise (or more-or-less delete) at some point anyway.
I removed the "install RHEL" and "install Ubuntu" scripts outright since I don't have any reasonable way to test them and don't plan to maintain them.