[skip ci] Replace .success with .table-success

app/views/notify/pipeline_success_email.html.haml

-%tr.success
+%tr.table-success
   %td{ style: "font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;padding:10px;border-radius:3px;font-size:14px;line-height:1.3;text-align:center;overflow:hidden;color:#ffffff;background-color:#31af64;" }
     %table.img{ border: "0", cellpadding: "0", cellspacing: "0", style: "border-collapse:collapse;margin:0 auto;" }
       %tbody