Unify reply comments specs

Note that the click_link "Reply" is now inside a "within".

This is due to the case of "legislation_annotation" before in the original test
no comment was created as it simply took the one created by default when creating
a "legislation_annotation".

```
  annotation = create(:legislation_annotation, author: citizen)
  comment = annotation.comments.first
```

Now to try to unify this test, we always create a comment, and in this case as we
also created the "legislation_annotation" we have 2 comments, so it is necessary
to add the "click_link" inside the "within".

spec/system/comments_spec.rb

@@ -306,6 +306,28 @@ describe "Comments" do
     end
   end
 
+  scenario "Reply" do
+    comment = create(:comment, commentable: resource)
+
+    login_as(user)
+    visit polymorphic_path(resource)
+
+    within "#comment_#{comment.id}" do
+      click_link "Reply"
+    end
+
+    within "#js-comment-form-comment_#{comment.id}" do
+      fill_in fill_text, with: "It will be done next week."
+      click_button "Publish reply"
+    end
+
+    within "#comment_#{comment.id}" do
+      expect(page).to have_content "It will be done next week."
+    end
+
+    expect(page).not_to have_css "#js-comment-form-comment_#{comment.id}"
+  end
+
   scenario "Errors on create" do
     login_as(user)
     visit polymorphic_path(resource)