Bug 17350: Purge old saved reports via cleanup_database

Bug 17350: Purge old saved reports via cleanup_database

To test:
apply patch
1 - have or create a report
2 - run your report via the command line with --store-results. Do this twice.
3 - update the saved_reports table to set date_run for one of your two saved results set to a datetime more than 5 days ago
4 - perl misc/cronjobs/cleanup_database.pl --reports 5 --verbose --confirm
5 - Koha tells you its deleting saved reports data from more than 5 days ago
6 - confirm in the database and the staff interface that it's done so

Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>