Bug 19071: Fix Members/IssueSlip.t

Bug 19071: Fix Members/IssueSlip.t

Resolve:
DBD::mysql::db do failed: Cannot delete or update a parent row: a foreign key constraint fails (`koha_master`.`clubs`, CONSTRAINT `clubs_ibfk_2` FOREIGN KEY (`branchcode`) REFERENCES `branches` (`branchcode`)) [for Statement "DELETE FROM branches"] at t/db_dependent/Members/IssueSlip.t line 44.

We do not need to delete all branches here.

Note: The test still needs attention for noisy userenv warns, but it should
pass now.

Test plan:
Run t/db_dependent/Members/IssueSlip.t

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>