Remove parenthesis around `image_tag`, remove empty state text center alignment

ee/app/views/shared/empty_states/_epics.html.haml

 .row.empty-state
   .col-xs-12
     .svg-content
-      = image_tag('illustrations/epics.svg')
-  .col-xs-12.text-center
+      = image_tag 'illustrations/epics/list.svg'
+  .col-xs-12
     .text-content
       %h4
         = _('Epics let you manage your portfolio of projects more efficiently and with less effort')