[CI][sycl-rel] Update sycl-rel CI (#18986)
This patch updates workflows and devops files on the sycl-rel-6_2
branch. In general it's a copy-paste from sycl branch, but
sycl-rel-nightly.yml was additionally updated (see the "remove redundant
parts" commit). We don't need these workarounds to launch the scheduled
run of sycl-rel nightly from sycl branch anymore, so I'm deleting
different *_ref stuff from this workflow.
