Revert "Provide systemd packages"
    
    This ended up causing weird issues with build dependencies, e.g.
    packages that 'BuildRequires: systemd' for systemd rpm macros no longer
    building because they ended up pulling in flatpak-runtime-config instead
    of systemd.
    
    This reverts commit ccc5a2ff39e95e4597fe6b41fb701141c2927f07.