MDL-81254 grade: ensure we always close the graded user iterator.

This ensures that the recordsets contained within are also closed
when we're done with them.

grade/report/singleview/index.php

@@ -238,6 +238,7 @@ if (($itemtype !== 'select') && ($itemtype !== 'grade_select') &&($itemtype !==
     $stickyfooter = new core\output\sticky_footer($footercontent);
     $stickyfooter = $OUTPUT->render($stickyfooter);
 
+    $gui->close();
 }
 
 echo $OUTPUT->render_from_template('gradereport_singleview/report', [

grade/report/user/index.php

@@ -170,7 +170,6 @@ if (has_capability('moodle/grade:viewall', $context)) {
                 echo $report->print_table(true);
             }
         }
-        $gui->close();
     } else { // Show one user's report.
         // Store the id of the current user item in a session variable which represents the last viewed item.
         $SESSION->gradereport_user["useritem-{$context->id}"] = $userid;
@@ -192,6 +191,8 @@ if (has_capability('moodle/grade:viewall', $context)) {
         $stickyfooter = new core\output\sticky_footer($userreportrenderer->user_navigation($gui, $userid, $courseid));
         echo $OUTPUT->render($stickyfooter);
     }
+
+    $gui->close();
 } else {
     // Students will see just their own report.
     // Create a report instance.

grade/report/user/renderer.php

@@ -131,7 +131,6 @@ class gradereport_user_renderer extends plugin_renderer_base {
         while ($userdata = $gui->next_user()) {
             $users[$userdata->user->id] = $userdata->user;
         }
-        $gui->close();
 
         $arraykeys = array_keys($users);
         $keynumber = array_search($userid, $arraykeys);