update the region of shield api

[oliviassss]

Issue

Description

Change the shield api region to cfg.Region from the hard coded "us-east-1", as this api is globally available now.
https://docs.aws.amazon.com/general/latest/gr/shield.html

 % aws shield get-subscription-state --region us-west-2
{
    "SubscriptionState": "ACTIVE"
}

 % aws shield get-subscription-state --region us-east-2
{
    "SubscriptionState": "ACTIVE"
}
% aws shield get-subscription-state --region ap-southeast-5
{
    "SubscriptionState": "ACTIVE"
}

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the docs directory)
• Manually tested
• Made sure the title of the PR is a good description that can go into the release notes

BONUS POINTS checklist: complete for good vibes and maybe prizes?! 🤯

• Backfilled missing tests for code in same general area 🎉
• Refactored something and made the world a better place 🌟

[M00nF1sh]

/lgtm
/approve

[k8s-ci-robot]

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This pull-request has been approved by: M00nF1sh, oliviassss

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