[Dependencies] Bump Go version

[weilerN]

📝 Description

Upgrade the Go toolchain and lint configurations to newer Go versions and golangci-lint v2, aligning with Nuclio’s lint version and YAML structure.

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🛠️ Changes Made

• Upgraded Go version to 1.25.x across go.mod and all relevant Dockerfiles.
• Updated base images in the Dockerfiles.
• Upgraded golangci-lint from v1.64.6 to v2.7.2.
• Migrated .golangci.yml to v2 config format.
• Refined linter setup:
  • Explicitly enabled a focused set of linters.
  • Moved formatting concerns (gofmt, gci) to formatters.
  • Removed legacy and unused configuration blocks.

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✅ Checklist

• I have tested the changes in this PR

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🧪 Testing

• Ran make lint locally with the updated golangci-lint version.
• Verified builds using updated Docker images.
• Ensured no new lint issues were introduced.

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🔗 References

• Ticket link: https://iguazio.atlassian.net/browse/NUC-718
• Solves current CI failure: https://github.com/v3io/scaler/actions/runs/20998404983/job/60361313767#step:4:93

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🚨 Breaking Changes?

• Yes (explain below)
• No

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🔍️ Additional Notes

• This is primarily a tooling and maintenance change with no runtime behavior impact