chore: onboard stepsecurity and apply security best practice

[ali-kafel]

Summary

This pull request improves the security and reliability of the GitHub Actions workflows for end-to-end and unit tests. The main changes include hardening the runners, specifying permissions more explicitly, and pinning action versions to specific commit SHAs for better reproducibility.

Security hardening:

• Added the step-security/harden-runner action to both .github/workflows/e2e-tests.yaml and .github/workflows/unit-tests.yaml to restrict network egress and enforce a global allowed endpoints policy. [1] [2]

Permissions improvements:

• Explicitly set permissions at the workflow and job levels, including contents: read and id-token: write, to follow the principle of least privilege. [1] [2]

Reliability and reproducibility:

• Updated actions/checkout and actions/setup-go to use pinned commit SHAs instead of version tags, ensuring consistent action versions across workflow runs. [1] [2]

Testing

Documentation

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Requested Reviewers: @mention