feat(ci): optimize go caching and wire up release security features

[nburchha]

What this does

• Optimizes Caching: Replaces the verbose, manual actions/cache blocks with the native cache: true flag in actions/setup-go.
• Enables Security: Adds the missing sboms, signs, and docker_signs blocks to .goreleaser.yaml so the Syft and Cosign tools in the release pipeline actually generate and attach SBOMs and signatures to our artifacts.