Bug 10933: The PurgeSearchHistory should be merge into the C4::Search::History module

Bug 10933: The PurgeSearchHistory should be merge into the C4::Search::History module

Since bug 10803 adds a C4::Search::History module, the
PurgeSearchHistory routine should be moved.

Test plan:
- run misc/cronjobs/cleanup_database.pl with the searchhistory param and
verify behavior is the same as before applying this patch.
- run prove t/Search/History.t

Signed-off-by: Joonas Kylmälä <j.kylmala@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>