Prevent SOECP exact spin evaluation with multi slater determinant wave functions due to incomplete code paths

[camelto2]

Please review the developer documentation
on the wiki of this project that contains help and requirements.

Proposed changes

Fixes a bug pointed out by @bkincaid256, which has to do with using SOECPs with multi slater determinants and getting the wrong total energies. The exact spin integration method was only implemented for single determinants. This PR prevents that code path.

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

Delete the items that do not apply

• Bugfix

Does this introduce a breaking change?

• No

What systems has this change been tested on?

mac

Checklist

Update the following with a yes where the items apply. If you're unsure about any of them, don't hesitate to ask. This is
simply a reminder of what we are going to look for before merging your code.

• Yes. This PR is up to date with current the current state of 'develop'
• Yes. Code added or changed in the PR has been clang-formatted
• No. This PR adds tests to cover any new code, or to catch a bug that is being fixed
• No. Documentation has been added (if appropriate)

[prckent]

Test this please

[prckent]

(nitrogen CI failure is unrelated and most likely due to issues with today's update to ROCm 6.2)

[ye-luo]

Test this please