[#24789][prism] Tiny staticcheck fix

[lostluck]

Fix accidental double import in prism/internal/jobservices/metrics_test.go

See #24789

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[damondouglas]

@lostluck LGTM

[lostluck]

The action tests are going to fail until #25545 is merged, but these side fixes will make that run eventually go green. :)