[AutoPR billing/resource-manager] Corrected the enum value to match it with actual implementation

[AutorestCI]

Created to sync Azure/azure-rest-api-specs#7782

[AutorestCI]

(message created by the CI based on PR content)

Installation instruction

Package azure-mgmt-billing

You can install the package azure-mgmt-billing of this PR using the following command:
pip install "git+https://github.com/Azure/azure-sdk-for-python@restapi_auto_7782#egg=azure-mgmt-billing&subdirectory=azure-mgmt-billing"

You can build a wheel to distribute for test using the following command:
pip wheel --no-deps "git+https://github.com/Azure/azure-sdk-for-python@restapi_auto_7782#egg=azure-mgmt-billing&subdirectory=azure-mgmt-billing"

If you have a local clone of this repository, you can also do:

• git checkout restapi_auto_7782
• pip install -e ./azure-mgmt-billing

Or build a wheel file to distribute for testing:

• git checkout restapi_auto_7782
• pip wheel --no-deps ./azure-mgmt-billing

Direct download

Your files can be directly downloaded here:

• azure-mgmt-billing-0.3.0.zip
• azure_mgmt_billing-0.3.0-py2.py3-none-any.whl

[AutorestCI]

This PR has been merged into #8613