Select the reduction algorithm using SLM when using icpx.

[ye-luo]

Proposed changes

Promote the current setting from Aurora build script to Intel compiler settings.
I found intel_gpu_bmg (battlemage, lunar lake) requires it to address the failing unit test https://cdash.qmcpack.org/tests/28817264

What type(s) of changes does this code introduce?

• Build related changes

Does this introduce a breaking change?

• No

What systems has this change been tested on?

epyc-server

Checklist

• • I have read the pull request guidance and develop docs
• • This PR is up to date with the current state of 'develop'
• • Code added or changed in the PR has been clang-formatted
• • This PR adds tests to cover any new code, or to catch a bug that is being fixed
• • Documentation has been added (if appropriate)

[prckent]

Thanks Ye.

(Safe to merge since the compiler options to use local shared memory are only modified for offload with Intel LLVM.)

[prckent]

Test this please