Replace old aws-portal:*Billing action in sample IAM policies

[konokenj]

BLEA creates some sample IAM Roles that include deprecated IAM action aws-portal:*Billing that should be replaced equivalent policies.

https://aws.amazon.com/jp/blogs/news/changes-to-aws-billing-cost-management-and-account-consoles-permissions/
https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/migrate-granularaccess-iam-mapping-reference.html

[suzukyz]

This issues was resolved by #583 .