OP-23081: Added aws region for sasl OAUTHBEARER mechanism

[utkarsh-opsmx]

We prefer small, well tested pull requests.

Please refer to Contributing to Spinnaker.

When filling out a pull request, please consider the following:

• Follow the commit message conventions found here.
• Provide a descriptive summary for your changes.
• If it fixes a bug or resolves a feature request, be sure to link to that issue.
• Add inline code comments to changes that might not be obvious.
• Squash your commits as you keep adding changes.
• Add a comment to @spinnaker/reviewers for review if your issue has been outstanding for more than 3 days.

Note that we are unlikely to accept pull requests that add features without prior discussion. The best way to propose a feature is to open an issue first and discuss your ideas there before implementing them.