Make checksecretparts required in CI

[mcastorina]

Description:

Enforces a lint check to ensure SecretParts is populated on all detectors.
Related: #4913

Checklist:

• Tests passing (make test-community)?
• Lint passing (make lint this requires golangci-lint)?

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Note

Medium Risk
CI now hard-fails when any detector constructs detectors.Result without populating SecretParts, which can newly block merges until detectors are compliant. The change is limited to GitHub Actions configuration but affects the repo’s merge gate.

Overview
Makes the checksecretparts CI job gating by removing the previous warning-only behavior and running it with -fail, so PRs fail when detector packages don’t populate SecretParts on detectors.Result.

Also updates the job’s comment/name to reflect that it is no longer best-effort.

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