MDL-72906 Quiz: Prevent scrollbar on multichoice

Remove negative margin from the "clear my choice" anchor.
With the negative margin, when the containing box height is calculated
the anchor's hidden style overflows beyond the boundary and triggers
the overflow:auto to add a scroll bar.

question/type/multichoice/renderer.php

@@ -323,7 +323,7 @@ class qtype_multichoice_single_renderer extends qtype_multichoice_renderer_base
         // Adds an hidden radio that will be checked to give the impression the choice has been cleared.
         $clearchoiceradio = html_writer::empty_tag('input', $clearchoiceradioattrs);
         $clearchoice = html_writer::link('#', get_string('clearchoice', 'qtype_multichoice'),
-            ['tabindex' => $linktabindex, 'role' => 'button', 'class' => 'btn btn-link ml-3 mt-n1 mb-n1']);
+            ['tabindex' => $linktabindex, 'role' => 'button', 'class' => 'btn btn-link ml-3 mt-n1']);
         $clearchoiceradio .= html_writer::label($clearchoice, $clearchoiceid);
 
         // Now wrap the radio and label inside a div.