PERF: Replace video and audio links in search blurb while indexing.

In the near future, we will be swtiching to PG headlines to generate the
search blurb. As such, we need to replace audio and video links in the
raw data used for headline generation. This also means that we avoid
replacing links each time we need to generate the blurb.

lib/discourse.rb

@@ -24,6 +24,8 @@ module Discourse
   end
 
   class Utils
+    URI_REGEXP = URI.regexp(%w{http https})
+
     # Usage:
     #   Discourse::Utils.execute_command("pwd", chdir: 'mydirectory')
     # or with a block