Apply translation string suggestion

Suggestion by @peterhegman

app/views/notify/new_merge_request_email.html.haml

 %p.details
-  #{link_to @merge_request.author_name, user_url(@merge_request.author)} created a #{link_to _("merge request"), @merge_request}:
+  = html_escape(_('%{userLinkStart}%{user}%{linkEnd} created a %{mrLinkStart}merge request%{linkEnd}:')) % {
+    userLinkStart: "<a href=\"#{user_url(@merge_request.author)}\">".html_safe,
+    user: @merge_request.author_name,
+    mrLinkStart: "<a href=\"#{merge_request_url(@merge_request)}\">".html_safe,
+    linkEnd: '</a>'.html_safe
+  }
 
 %p
   .branch