Use `--client-id` for user-assigned managed identity authentication

[jiasli]

Azure CLI introduced 3 new arguments --client-id, --object-id and --resource-id to replace --username for user-assigned managed identity authentication: Azure/azure-cli#30525.

Since azure/login only supports client-id: https://github.com/marketplace/actions/azure-login#login-with-user-assigned-managed-identity, it should map client-id to --client-id instead of --username.