Revert t function to returning the plain string by default

Add `t.html` function for getting the string with the `lang` attribute

modules/validations/help_request.js

@@ -44,7 +44,7 @@ export function validationHelpRequest(context) {
                 .enter()
                 .append('div')
                 .attr('class', 'issue-reference')
-                .html(t('issues.fixme_tag.reference'));
+                .html(t.html('issues.fixme_tag.reference'));
         }
     };