ZOOKEEPER-5060: Update GitHub Action versions

[PDavid]

For example Checkout v7 has a safer fork pull request handling. See: https://github.com/actions/checkout

I pinned GitHub Actions to full commit SHAs which is a security best practice that locks workflows to immutable versions, preventing supply chain attacks where mutable tags (like @v4 or @main) are updated or compromised.

Why Pin to SHA?

• Immutability: Unlike tags, a 40-character SHA never changes; if a repository is compromised, future commits will have different hashes, protecting your pipeline from running malicious code.
• Reproducibility: Ensures every workflow run executes the exact same code, eliminating "works on my machine" issues caused by silent tag updates.
• Security: Mitigates risks associated with tag hijacking or force-pushes that can inject vulnerabilities into trusted action references.

[PDavid]

A test failed but it should be unrelated because I only changed the GH Action versions on this branch:

[ERROR]   SnapshotAndRestoreCommandTest.testSnapshotAndRestoreCommand_streaming:168->validateSnapshotMetrics:398 expected: <true> but was: <false>

[PDavid]

If you will have some time @anmolnar or @phunt can you please take a look?

[anmolnar]

🚢

[PDavid]

Forgot to mention that I'll do this for the older active branches as well.

[PDavid]

Created backports here:

• ZOOKEEPER-5060: Update GitHub Action versions #2418
• ZOOKEEPER-5060: Update GitHub Action versions #2419