Switch orion site config to zlib instead of zlib-ng

[climbfuji]

Summary

This is similar to what was done for the release/spack-stack-1.7.0 branch on S4. With [email protected] (will be used on Orion until May 22nd, 2024), zlib-ng wrecks havoc: cannot run git clone, cannot run pip install, etc.

Testing

Used on Orion to rebuild the spack-stack-1.7.0 installs of ue and gsi-addon-env with Intel (left GNU alone).

Applications affected

n/a

Systems affected

Orion until it's rebuilt in May

Dependencies

n/a

Issue(s) addressed

n/a

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.