FIX: stop stripping local onebox links from tracker

When a onebox was made to a local topic it was not tracked using link
tracker

lib/onebox/templates/discourse_topic_onebox.hbs

@@ -1,4 +1,4 @@
-<aside class='quote' data-post="1" data-topic="{{topic}}">
+<aside class='quote topic-onebox' data-post="1" data-topic="{{topic}}">
   <div class='title'>
     {{{avatar}}}
     <a href="{{original_url}}">{{{title}}}</a> {{{category_html}}}

lib/pretty_text.rb

@@ -284,7 +284,7 @@ module PrettyText
     links = []
     doc = Nokogiri::HTML.fragment(html)
     # remove href inside quotes & elided part
-    doc.css("aside.quote a, .elided a").each { |l| l["href"] = "" }
+    doc.css("aside.quote:not(.topic-onebox) a, .elided a").each { |l| l["href"] = "" }
 
     # extract all links from the post
     doc.css("a").each { |l|