Render fulfillment container only when applicable

Why these changes are being introduced:

The fulfillment link container currently renders
as an empty div when no links are available. This
pollutes the DOM and affects spacing.

Relevant ticket(s):

- [USE-611](https://mitlibraries.atlassian.net/browse/USE-611)

How this addresses that need:

This removes the parent div if no fulfillment links
are present.

Side effects of this change:

None.

Author: jazairi

app/javascript/controllers/content_loader_controller.js

@@ -12,16 +12,23 @@ export default class extends Controller {
       .then(response => response.text())
       .then(html => {
         const parentElement = this.element.parentElement;
-        // Replace the entire element with the fetched HTML
-        this.element.outerHTML = html;
-        // Hide primo links if libkey link is present
-        if (parentElement.querySelector('.libkey-link')) {
-          const resultGet = parentElement.closest('.result-get');
-          if (resultGet) {
-            const primoLinks = resultGet.querySelectorAll('.primo-link');
-            // removing instead of hiding to avoid layout issues when selecting which link to highlight
-            primoLinks.forEach(link => link.remove());
+        // Strip HTML comments and trim whitespace
+        const cleanedHtml = html.replace(/<!--[\s\S]*?-->/g, '').trim();
+        // Replace the entire element with the fetched HTML, or remove if empty
+        if (cleanedHtml) {
+          this.element.outerHTML = cleanedHtml;
+          // Hide primo links if libkey link is present
+          if (parentElement.querySelector('.libkey-link')) {
+            const resultGet = parentElement.closest('.result-get');
+            if (resultGet) {
+              const primoLinks = resultGet.querySelectorAll('.primo-link');
+              // removing instead of hiding to avoid layout issues when selecting which link to highlight
+              primoLinks.forEach(link => link.remove());
+            }
           }
+        } else {
+          // Remove result-get container (no fulfillment links)
+          parentElement.remove();
         }
       })
   }