Merge branch 'fix-markdown-code-mr-discussion' into 'master'

Fix markdown code highlighting in mr discussion

Closes #47521

See merge request gitlab-org/gitlab-ce!19564

app/assets/stylesheets/bootstrap_migration.scss

@@ -107,7 +107,7 @@ code {
   background-color: $red-100;
   border-radius: 3px;
 
-  .code & {
+  .code > & {
     background-color: inherit;
     padding: unset;
   }