This reverts commit 2b9bab23df.
Doesn't work. Time to drop flatpak/appimage builds for aarch64, I'd say.
Probably not worth the hassle (assuming they're barely used anyway, if
at all).
Switching to an Arch based build process for easier maintenance and
using specific runners for tasks where that might be necessary.
Right now, parent/child pipelines for somewhat parallel builds for
different architectures / semi-independent pak-builds don't seem to
properly work yet due to `trigger:` not being recognized when it should,
so that's not yet implemented.
