fix: remove duplicate flatpaks from recipe.yml

Having duplicates in the yafti.yml where a package exists in multiple groups *currently* causes subtle bugs in yafti, such as a package becoming deselected even though the entire group is "selected". That causes great confusion when users try to install "Core GNOME Apps" without realizing that they won't receive the Extension Manager (for example), since it existed in a different group too and therefore became automatically unchecked in yafti.

A future yafti update will make all duplicate flatpak names illegal (a yml validation error), so this change also prepares us for that, by removing all duplicates.

As for why I added Krita: Since there was only one unique app in the recipe.yml, I needed another random, popular app to fit the example of "this is a selection of example apps", there's nothing more to it than that. ;)

recipe.yml

@@ -87,11 +87,5 @@ firstboot:
   # the "just setup-flatpaks" command from our "custom.just" template file.
   # This is just an example selection:
   flatpaks:
-    - org.mozilla.firefox
-    - org.mozilla.Thunderbird
-    - com.mattjakeman.ExtensionManager
-    - org.libreoffice.LibreOffice
-    - org.gnome.DejaDup
-    - org.gustavoperedo.FontDownloader
-    - com.github.tchx84.Flatseal
     - io.github.celluloid_player.Celluloid
+    - org.kde.krita