Patch waagent.conf to add firewall rules

[liunan-ms]

Merge Checklist

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

• The toolchain has been rebuilt successfully (or no changes were made to it)
• The toolchain/worker package manifests are up-to-date
• Any updated packages successfully build (or no packages were changed)
• Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
• Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
• All package sources are available
• cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
• LICENSE-MAP files are up-to-date (./SPECS/LICENSES-AND-NOTICES/data/licenses.json, ./SPECS/LICENSES-AND-NOTICES/LICENSES-MAP.md, ./SPECS/LICENSES-AND-NOTICES/LICENSE-EXCEPTIONS.PHOTON)
• All source files have up-to-date hashes in the *.signatures.json files
• sudo make go-tidy-all and sudo make go-test-coverage pass
• Documentation has been updated to match any changes to the build system
• Ready to merge

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Summary

What does the PR accomplish, why was it needed?
Add EnableFirewall flag to waagent.conf to protect access to Azure host node services.

Change Log

• Patch waagent.conf to add firewall rules to protect access to Azure host node

Does this affect the toolchain?

NO

Associated issues

Links to CVEs

Test Methodology

• Pipeline build id: https://dev.azure.com/mariner-org/mariner/_build/results?buildId=494151&view=results

[eric-desrochers]

@narrieta for visibility and reviewal from a WALA team perspective.

[narrieta]

lgtm

[hbeberman]

Can you verify that this works as intended on an AKS node?

Our AKS images leave management of iptables up to Kubernetes, so I want to make sure the rules this writes aren't interfering or getting overwritten.