Bug 34972: Add tests for ModReservesCancelAll

Bug 34972: Add tests for ModReservesCancelAll

To test:
1. Apply this patch only
2. prove t/db_dependent/Koha/Holds.t
--> Tests pass
3. Apply the other patch
4. prove t/db_dependent/Koha/Holds.test
--> Tests still pass

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit d71f5272021b54849e5854d3a7b8ecb1f30d9414)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>