Update Ursa site config for building spack-stack develop 2025/10/02 unified environments

[climbfuji]

Description

Update configs/sites/tier1/ursa/compilers.yaml and configs/sites/tier1/ursa/packages_oneapi.yaml for building unified environment on Ursa for spack-stack develop as of 2025/10/02.

Tested on Ursa, environments built cleanly for both compilers.

Note that the Ursa site config will be updated shortly again on the feature/update_to_spack_v1 branch, this will likely include reverting back to external compiler runtime libraries.

Dependencies

None

Issues addressed

None. Related to automation work (see #1788).

Applications affected

None

Systems affected

Ursa

Testing

• CI: Note whether the automatic tests (GitHub actions tests that run automatically for every commit) pass or not
  • GitHub actions CI tests pass in progress, but not necessary (only site config changes)
  • GitHub actions CI tests do not pass (provide explanation)
  • GitHub actions CI tests skipped (provide explanation if necessary)
• New tests added: List and describe any new tests added to GitHub actions
  • ...
• Additional testing: Add information on any additional tests conducted
  • Tested on Ursa, unified environments built cleanly for both compilers.

Checklist

• This PR addresses one issue/problem/enhancement or has a very good reason for not doing so.
• These changes have been tested on the affected systems and applications.
• All dependency PRs/issues have been resolved and this PR can be merged.
• All necessary updates to the documentation on readthedocs are included in this PR
  • For site config updates, check in particular doc/source/PreConfiguredSites.rst and doc/source/MaintainersSection.rst
• All necessary updates to the spack-stack wiki will be made when this PR is merged