Bug 38162: Pass the rota_id correctly when deleting

Bug 38162: Pass the rota_id correctly when deleting

To test:

1. Enable StockRotation
2. Got to Cataloging -> Stock rotation
3. Create a new Rota
4. Try to delete it
5. See the error "Can't call method "delete" on an undefined value at /kohadevbox/koha/tools/stockrotation.pl line 231"
6. APPLY PATCH
7. Try again, the rota should be deleted properly.

Signed-off-by: Laura ONeil <laura@bywatersolutions.com>
Signed-off-by: Alyssa <alyssa.drake@bywatersolutions.com>
Signed-off-by: Emily Lamancusa <emily.lamancusa@montgomerycountymd.gov>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>