Fail to run azd pipeline config --provider azdo for todo-nodejs-mongo-aks

[puicchan]

This is transferred from Azure/azure-dev#4348.

Describe the issue:
Running the azd pipeline config --provider azdo command fails with the following error message:
image

Repro Steps:

Login in with command: azd auth login.
Run command: azd init -t todo-nodejs-mongo-aks -b staging.
Run command: azd pipeline config --provider azdo.
Environment:

Template: todo-nodejs-mongo-aks.
Branch: staging
OS: Windows, MacOS.
Azd version: azd version 1.11.0-beta.1-pr.4140256 (commit Azure/azure-dev@b6402de) and azd version 1.11.0-beta.1-daily.4152592 (commit Azure/azure-dev@e2ff8ba)
Expected behavior:
azd pipeline config --provider azdo commands can be run successfully.

From Victor:
Looks like AZURE_PRINCIPAL_TYPE is not set during azd pipeline config and it is empty during CI run, making the runner to take the value of the literal ${AZURE_PRINCIPAL_TYPE} instead of replacing it with a value from the env.

This is an issue in the template configuration. The azure.yaml should define the AZURE_PRINCIPAL_TYPE in the pipeline->variables as a required ENV VAR to set during azd pipeline config