Issue Summary

Hello team,

When trying to configure Actions for teams using "AWS Systems Manager" getting the error 

STS is not activated in this region for account:xyz123abc123. Your account administrator can activate STS in this region using the IAM Console. (Service: AWSSecurityTokenService; Status Code: 403; Error Code: RegionDisabledException 

This issue appeared when the STS https://sts.us-west-2.amazonaws.com/ is disabled

This is reproducible on Data Center: (yes) / (no)
Yes

Steps to Reproduce

1. Teams > Actions > Create Action channel with AWS Systems Manager with "US East (N. Virginia)" or any other region.
2. While testing this make sure AWS Security Token Service (STS) is disabled for "US West (Oregon)"
3. Continue to Add Action in the Manage Actions section selecting "AWS Systems Manager" for type and select the newly created Action channel for the Action channel

Expected Results

Since the "US East (N. Virginia)" region has STS active, get the Action created.

Actual Results

But getting the below error

STS is not activated in this region for account:xyz123abc123. Your account administrator can activate STS in this region using the IAM Console. (Service: AWSSecurityTokenService; Status Code: 403; Error Code: RegionDisabledException 

Workaround

The only workaround is to Activate STS for the "US West (Oregon)" region and continue to create the action channel/Actions