fix: fix request.is_ajax() deprecation warning (#33055)

* fix: fix request.is_ajax() deprecation warning

cms/djangoapps/contentstore/views/error.py

@@ -18,7 +18,7 @@ def jsonable_error(status=500, message="The Studio servers encountered an error"
     def outer(func):
         @functools.wraps(func)
         def inner(request, *args, **kwargs):
-            if request.is_ajax():
+            if request.headers.get('x-requested-with') == 'XMLHttpRequest':
                 content = dump_js_escaped_json({"error": message})
                 return HttpResponse(content, content_type="application/json",  # lint-amnesty, pylint: disable=http-response-with-content-type-json
                                     status=status)

cms/djangoapps/maintenance/views.py

@@ -94,7 +94,7 @@ class MaintenanceBaseView(View):
         """
         A short method to render_to_response that renders response.
         """
-        if self.request.is_ajax():
+        if self.request.headers.get('x-requested-with') == 'XMLHttpRequest':
             return JsonResponse(self.context)
         return render_to_response(self.template, self.context)