Fix login with az cli

[LaurentLesle]

az cli required the PEM Private Key to be encrypted. When downloaded from Keyvault, the key is not password protected. This PR provides the fix.

More context > https://github.com/Azure/azure-cli/issues/7489#issuecomment-1959439989

[learn-build-service-prod[bot]]

Learn Build status updates of commit 982bb98:

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