Remove last remaining `reference_only_path` usages

app/views/notify/_note_message.html.haml

 %div
-  = markdown(@note.note, reference_only_path: false)
+  = markdown(@note.note, pipeline: :email)

app/views/notify/new_issue_email.html.haml

 -if @issue.description
-  = markdown(@issue.description, reference_only_path: false)
+  = markdown(@issue.description, pipeline: :email)
 
 - if @issue.assignee_id.present?
   %p

app/views/notify/new_merge_request_email.html.haml

@@ -6,4 +6,4 @@
     Assignee: #{@merge_request.author_name} → #{@merge_request.assignee_name}
 
 -if @merge_request.description
-  = markdown(@merge_request.description, reference_only_path: false)
+  = markdown(@merge_request.description, pipeline: :email)