title: Kibana filter regex 'string starts with' doesn't work
body: <p>In Kibana chart I want to filter all urls that start with string <code>CANCELLED</code> so I wrote a regex: <code>^CANCELLED.*</code> but when I use filter in Discover tab then I notice that filter doesn't work properly because it also accepts urls with phrase <code>CANCELLED</code> inside of an url. </p>
  
  <p>Is it because Kibana regex uses other character than caret for the beginning of a string?</p>