sycl : fix test-backend-ops CI break && restore Kronecker product FWHT support (#28016) (#28254)
* Reapply "sycl : add Kronecker product FWHT support for sizes 384, 640, 768, 12…" (#28184)
This reverts commit c845263f8b7d60113e213a3bd2d5cc6472ccf204.
* tests : fix unused variable M in test-backend-ops
* tests: fix trailing space error and isolate kronecker tests for sycl backend only