MDL-77542 mod_assign: remove duplicate grade heading from grader.

It's already part of the subsequent rendered form.

mod/assign/locallib.php

@@ -4117,7 +4117,7 @@ class assign {
             // and show errors.
             $mform->is_validated();
         }
-        $o .= $this->get_renderer()->heading(get_string('gradenoun'), 3);
+
         $o .= $this->get_renderer()->render(new assign_form('gradingform', $mform));
 
         if (count($allsubmissions) > 1) {
@@ -4303,7 +4303,7 @@ class assign {
                                                '',
                                                array('class'=>'gradeform'));
         }
-        $o .= $this->get_renderer()->heading(get_string('gradenoun'), 3);
+
         $o .= $this->get_renderer()->render(new assign_form('gradingform', $mform));
 
         if (count($allsubmissions) > 1 && $attemptnumber == -1) {