Merge branch '49192-comment-alignment' into 'master'

Resolve "Toggle comments button icon is misaligned"

Closes #49192

See merge request gitlab-org/gitlab-ce!20756

app/assets/stylesheets/pages/diff.scss

@@ -16,6 +16,7 @@
     svg {
       vertical-align: middle;
+      top: -1px;
     }
   }