Use auto generated api for markdown input

core/templates/core/widgets/markdown_textarea.jinja

@@ -7,9 +7,7 @@
   <script type="text/javascript">
     addEventListener("DOMContentLoaded", (event) => {
       easymdeFactory(
-        document.getElementById("{{ widget.attrs.id }}"),
-        "{{ markdown_api_url }}",
-      );
+        document.getElementById("{{ widget.attrs.id }}"));
     })
   </script>
 </div>