Update Rust template
- Don't enable cargo build logging, it's very not very helpful, and disables the build progressbar
- Move cargo-home outside of the
target
folder, as this seems to confuse R-A sometimes - Remove invalid env variable from flatpak manifest, as it causes problems (eg. triggering a complete rebuild with all cargo dependencies each time instead of doing a partial build). I still couldn't figure out why this was/(is?) needed at all