Bug 26462: Don't delete existing data for tests

Bug 26462: Don't delete existing data for tests

These tests generate their own items, patrons, and circ rules. Existing
system data will not affect the results of the tests. We do not need
to delete information.

You may be able to notice the difference in speed of tests depending on your system. It should
be faster after applying

To test:
1 - Before applying patch:
    prove -v t/db_dependent/Holds.t
2 - It passes
3 - Apply patch
4 - prove -v t/db_dependent/Holds.t
5 - It passes

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>