MDL-77288 quiz: Horizontally align feedback to the border & full width.

Probably from historical reasons and because of layout of former Moodle
versions the container the feedback is situated in has 70% width and is
indented. In nowadays themes this looks weird and gives visual inconsistency.

mod/quiz/styles.css

@@ -265,21 +265,6 @@ table.quizattemptsummary .noreviewmessage {
     margin-right: auto;
 }
 
-#page-mod-quiz-view .generalbox#feedback {
-    width: 70%;
-    margin-left: auto;
-    margin-right: auto;
-    padding-bottom: 15px;
-}
-
-#page-mod-quiz-view .generalbox#feedback h2 {
-    margin: 0;
-}
-
-#page-mod-quiz-view .generalbox#feedback h3 {
-    text-align: left;
-}
-
 #page-mod-quiz-view .generalbox#feedback .overriddennotice {
     text-align: center;
     font-size: 0.7em;