Apps: Remove symlinks which are no longer needed

[newhoa]

Removed

• drakstats (Seems it was a part of old Mandrake/Mandriva, can't find modern mentions of it)
• file-roller (Gnome provides their own differently-named icon, so this wasn't being used anyway)
• gtklp* (not used, app makes its own xpm-based icons)
• nm-vpn-standalone-lock (removed in nm-applet) (https://gitlab.gnome.org/GNOME/network-manager-applet/-/commit/4cf18cc)
• plugin-* (only used for ccsm, and we only provided 5 out of 60+ which looks bad/broken/incomplete. better they use their own all-matching icons.)
• system-installer (not used)
• system-software-installer (not used)

Renamed/Updated

• system-software-installer > system-software-install system-software-install is the correct freedesktop.org name. Resymlinked package icons (rpmdrake, synaptic, update-notifier, yumex > yumex-dnf)
• system-upgrade (deleted duplicate icon from /apps, kept in /actions)