SYCL: optimized repeat_back kernel (3× fewer asm instructions, 2× faster)Feature...

SYCL: optimized repeat_back kernel (3× fewer asm instructions, 2× faster)Feature/sycl repeat back opt (#16869)

* SYCL repeat_back v1 — add core op + switch case

* Implement repeat_back SYCL operation and minor fixes

* SYCL: optimize repeat_back kernel

* Remove Hebrew comment from repeat_back.cpp

* Remove comments for code clarity

Removed comments to clean up the code.

* Fix formatting in ggml-sycl.cpp

* Formatted lambda according to legacy style. No logic changes

* Remove blank line in repeat_back.cpp

Remove unnecessary blank line before assigning acc to dst_dd.