tilix, gtkd, zita-njbridge and helm removal

tilix, gtkd, zita-njbridge, helm were removed from and are no longer available on nexus.

The current alternative is to use the offical versions from the archlinux repo (tilix, gtkd, zita-njbridge, helm).

Previous Packages are available in the nexus-archive (tilix, gtkd, zita-njbridge, helm) for a limited time.