vimPlugins.rustaceanvim: move to luaPackagePlugins

pkgs/applications/editors/vim/plugins/luaPackagePlugins.nix

···
     "rest-nvim"
     "rocks-config-nvim"
     "rocks-nvim"
+    "rustaceanvim"
     "rtp-nvim"
     "telescope-manix"
     "telescope-nvim"

pkgs/applications/editors/vim/plugins/overrides.nix

···
 
   });
 
-  rustaceanvim = neovimUtils.buildNeovimPlugin {
+  rustaceanvim = super.rustaceanvim.overrideAttrs {
     checkInputs = [
       # Optional integration
       self.neotest
     ];
-    luaAttr = luaPackages.rustaceanvim;
   };
 
   rust-tools-nvim = super.rust-tools-nvim.overrideAttrs {