Fix SPHINCS+ naming in CT tests [skip ci]

[SWilson4]

Looks like the names were overwritten by mistake during the recent ML-DSA / ML-KEM additions, leading to CI failures.

Fixes #1718.

• Does this PR change the input/output behaviour of a cryptographic algorithm (i.e., does it change known answer test values)? (If so, a version bump will be required from x.y.z to x.(y+1).0.)
• Does this PR change the list of algorithms available -- either adding, removing, or renaming? Does this PR otherwise change an API? (If so, PRs in fully supported downstream projects dependent on these, i.e., oqs-provider will also need to be ready for review and merge by the time this is merged.)

[baentsch]

LGTM. Thanks for finding the reason, @SWilson4 . Looking at #1626 that apparently necessitated this PR, I wonder how this could happen given we have a merge CI checking for unintended changes (e.g., to algs not impacted by a change to copy_from_upstream.yml)? Something worth while improving to avoid this may happen again?

[dstebila]

Thanks for catching this!