Fix note header author and time ago wrapping in parallel diff

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/32801

app/assets/stylesheets/pages/notes.scss

@@ -380,6 +380,12 @@ ul.notes {
   padding-bottom: 5px;
 }
 
+.note-header-author-name {
+  @media (max-width: $screen-xs-max) {
+    display: none;
+  }
+}
+
 .note-headline-light {
   display: inline;
 
@@ -717,9 +723,8 @@ ul.notes {
 // Merge request notes in diffs
 .diff-file {
   // Diff is side by side
-  .notes_content.parallel .note-header .note-headline-light {
+  .notes_content.parallel .note-header .note-header-author-name {
     display: block;
-    position: relative;
   }
   // Diff is inline
   .notes_content .note-header .note-headline-light {

app/views/shared/notes/_note.html.haml

@@ -18,7 +18,7 @@
       .note-header
         .note-header-info
           %a{ href: user_path(note.author) }
-            %span.hidden-xs
+            %span.note-header-author-name
               = sanitize(note.author.name)
             %span.note-headline-light
               = note.author.to_reference