[#33805] Only try to find a search page if the request Itemid is not a search page.

Also, find search pages by component id, not link string

Fixes this tracker item: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33805
I think you can use the component property here as well. This way you don't even have to use the component helper to get the id.