vimPlugins: don't build generated plugins on hydra

Building generated plugin is really simple and its cost to serve from
hydra greatly outcomes cost of locally building.

This also allows us to merge big rebuilds, where each rebuild is fairly
simple, to master without delaying next branch update by a few hours
(see https://github.com/NixOS/nixpkgs/pull/368843#issuecomment-2564770782)

pkgs/applications/editors/vim/plugins/update.py

@@ -112,6 +112,7 @@ class VimEditor(pluginupdate.Editor):
     version = "{plugin.version}";
     src = {src_nix};
     meta.homepage = "{repo.uri}";
+    meta.hydraPlatforms = [ ];
   }};
 
 """.format(