MDL-52940 core_backup: prevent always displaying logs

backup/backup.php

@@ -138,7 +138,9 @@ if ($backup->get_stage() == backup_ui::STAGE_FINAL) {
     }
 
     // Get HTML from logger.
-    $loghtml = $logger->get_html();
+    if ($CFG->debugdisplay) {
+        $loghtml = $logger->get_html();
+    }
 
     // Hide the progress display and first backup step bar (the 'finished' step will show next).
     echo html_writer::end_div();

backup/restore.php

@@ -110,7 +110,9 @@ if (!$restore->is_independent()) {
             // Do actual restore.
             $restore->execute();
             // Get HTML from logger.
-            $loghtml = $logger->get_html();
+            if ($CFG->debugdisplay) {
+                $loghtml = $logger->get_html();
+            }
             // Hide this section because we are now going to make the page show 'finished'.
             echo html_writer::end_div();
             echo html_writer::script('document.getElementById("executionprogress").style.display = "none";');