Let it work when no metadata is available

[BEvgeniyS]

As per EKS security best practices, we'd like to restrict access to EC2 metadata. Serviceaccount roles allow to assume IAM roles by pods. Unless I'm missing something, there's no reason for the program to fail when there's no metadata

This adds an option to override the region using standard environment variables - AWS_DEFAULT_REGION or AWS_REGION

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