[CODEOWNERS] Add llvm-reviewers-benchmarking to CODEOWNERS (#17547)
Scripts enabling CI for benchmarking has gotten pretty big and
complicated: https://github.com/intel/llvm/pull/17545
Most of this code were developed by the UR team, and thus it no longer
makes sense to ask dpcpp-devops-reviewers for PR approvals. This PR
updates CODEOWNERS to ask llvm-reviewers-benchmarking for benchmarking
scripts instead.
**Note:** The current path here puts `/devops/scripts/benchmarks` under
llvm-reviewers-benchmarking: This path currently does not exist, but is
chosen on purpose in anticipation for
https://github.com/intel/llvm/pull/17545.
The folder `/devops/scripts/benchmarking` will be removed in the future
as a part of the effort to unify SYCL and UR benchmarking CI
infrastructure; See https://github.com/intel/llvm/pull/17229