fix: populate custom resources CDK stacks with region and account (#12575)

[bombguy]

Description of changes

Custom resource should populate with region and account from CDK default variables.

https://docs.aws.amazon.com/cdk/v2/guide/environments.html

Issue #, if available

#12575

Description of how you validated changes

Manual testing, unit test & e2e tests added

Checklist

• [X] PR description included
• [X] yarn test passes
• [X] Tests are changed or added

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[joeykay9]

What's happening with this PR? @bombguy @sobolk