Fix more duplicated JS code

Strangely enough, this seems to result from the upstream merge:
https://gitlab.com/gitlab-org/gitlab-ee/commit/adbfff09e3e97eaa2e77b2888c148989e7d5444c#a66b0cb7d7efb8c153da597f254084a47dae4a38Signed-off-by: Rémy Coutable <remy@rymai.me>

app/assets/javascripts/environments/components/environments_table.js

@@ -61,12 +61,6 @@ export default {
     folderUrl(model) {
       return `${window.location.pathname}/folders/${model.folderName}`;
     },
-
-    isLoadingFolderContent: {
-      type: Boolean,
-      required: false,
-      default: false,
-    },
   },
 
   template: `