Bug 38495: Use JS to submit form to cancel background jobs

Bug 38495: Use JS to submit form to cancel background jobs

This patch adjusts the link to cancel jobs to be submitted as a POST with cud-cancel operation

To test:
1 - Stop your long tasks bacground jobs worker
   sudo koha-worker --stop --queue long_tasks kohadev
2 - Stage a file for import
3 - Administration -> Manage jobs
4 - See your new job
5 - Click 'cancel'
6 - It didn't work
7 - Apply patch
8 - Browse to jobs again
9 - Click 'Cancel'
10 - Job is successfully cancelled

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
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 d047776630152a9e2b16c7797aaac600c0dff6e2)
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>