Provide multi-version package repositories instead of just latest version only

Currently we only provide the latest "point" release of our release series in our rpm and deb repositories only.

yum and apt-get (probably zypper, too) allow to specify a specific package version instead of the latest one. For this the requested version has to still be available on the repository server, or in the local package cache, though.

When we recommend to not install the latest version for a while, like we just recently did with MDEV-14799 in some cases, this is only possible by manual download and installation of packages using rpm or dpkg directly, but not via repository tools like apt-get, yum (, zypper?)

By keeping the last n point releases around, with n > 1, (e.g. 3 or 4 sounds like a sensible amount to me) "do not install the latest for now" would be possible in a much more convenient way.