Merge branch 'discussion-fixes-2' into 'master'

Fix vertical line alignment in discussion & diff border-radius

Closes #53975

See merge request gitlab-org/gitlab-ce!23075

app/assets/stylesheets/pages/note_form.scss

@@ -241,7 +241,7 @@ table {
   .discussion-reply-holder {
     background-color: $white-light;
     padding: 10px 16px;
-    border-radius: 0 0 $border-radius-default $border-radius-default;
+    border-radius: 0 0 3px 3px;
     &.is-replying {
       padding-bottom: $gl-padding;

app/assets/stylesheets/pages/notes.scss

@@ -28,7 +28,7 @@ $note-form-margin-left: 72px;
 }
 .main-notes-list {
-  @include vertical-line(39px);
+  @include vertical-line(36px);
 }
 .notes {