[AKS] Set network profile when using basic load balancer.

[JunSun17]

---

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• Have you run azdev style <YOUR_EXT> locally? (pip install azdev required)
• Have you run python scripts/ci/test_index.py -q locally?

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[azuresdkci]

If this PR is for a new extension or change to an existing extension, use the following to try out the changes in this PR:

docker run -it microsoft/azure-cli:latest
export EXT=<NAME>
pip install --upgrade --target ~/.azure/cliextensions/$EXT "git+https://github.com/JunSun17/azure-cli-extensions.git@jusu-basic-lb#subdirectory=src/$EXT&egg=$EXT"

[JunSun17]

This is for #2138

[robbiezhang]

please verify whether you need to set network_plugin="kubenet" like L986

[JunSun17]

Verified in live test that network_plugin is not needed, it default to kubenet.

[yonzhan]

aks

[yungezz]

hi @fengzhou-msft could you pls help to review the PR?