Resolve "Specific Async Script Loading by using a Page Variable"

What does this MR do?

It makes it possible to set script loading on a specific page to defer. Simply set @page_defer_javascript to true and all scripts will get the defer="defer" attribute.

Why was this MR needed?

To boost performance already on specific pages. Later on we can reuse the javascript_tag overwrite exactly in the opposite way so all scripts are defer except specific ones.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #34904 (closed)

app/assets/javascripts/behaviors/toggler_behavior.js

@@ -30,16 +30,14 @@ $(() => {
     }
   });
 
-  setTimeout(() => {
-    // If we're accessing a permalink, ensure it is not inside a
-    // closed js-toggle-container!
-    const hash = window.gl.utils.getLocationHash();
-    const anchor = hash && document.getElementById(hash);
-    const container = anchor && $(anchor).closest('.js-toggle-container');
+  // If we're accessing a permalink, ensure it is not inside a
+  // closed js-toggle-container!
+  const hash = window.gl.utils.getLocationHash();
+  const anchor = hash && document.getElementById(hash);
+  const container = anchor && $(anchor).closest('.js-toggle-container');
 
-    if (container) {
-      toggleContainer(container, true);
-      anchor.scrollIntoView();
-    }
-  }, 0);
+  if (container) {
+    toggleContainer(container, true);
+    anchor.scrollIntoView();
+  }
 });