Consolidate supported distributions/operating systems

While working on adding RHEL 10 support, I came across the detection code for some very old distributions and I wonder wether we still need to keep that detection code.

For example Ubuntu 4.10 or Debian 5.0 or CentOS 6.0 or the openSUSE detection block.

While it is still possible to get updates for CentOS 6 via paid update support, I doubt that the same is possible to get for such old Ubuntu/Debian versions. Tied to this issue might be also the question what we want to do with the sysv-initd support since almost every major distribution shifted to systemd.

This is not something that we need to address immediately, but I would like to bring this topic up for discussion.