community/*: use apps.gnome.org short links
At some point, the apps.gnome.org site changed the URL format to a shorter one, containing only the app name. Update package URLs that still use the old URL format. (The old URLs redirect to the new ones, this is just to keep things neat and tidy.)
testing/gnome-metronome
uses the old URL format but the URL 404s as the app has been dropped from GNOME Circle; as such, I've left it as-is.
(Inspired by !76700 (merged).)
Edited by knuxify