Bug 10952: (follow-up) clear seach history from session after saving it to DB

Bug 10952: (follow-up) clear seach history from session after saving it to DB

This patch makes sure that the search history from an
anonymous session is cleared from the session after a user
logs in (and the session history is saved to that user's
record in the database).  This fixes a problem where the
search history from the session got repeatedly added to the
database each time the user did something while logged
into the OPAC.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>