AwsClient for security_credentials retrieved tokens retrieveSubjectToken(): should reject when AWS region is not determined failed

[flaky-bot[bot]]

Note: #1567 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky.

---

commit: d8e5eb9994d2157a937543ed9f7d911b9e9db413 buildURL: Build Status, Sponge status: failed

Test output

Expected values to be strictly deep-equal:
+ actual - expected

+ Comparison {}
- Comparison {
-   status: 500
- }
AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal:
+ actual - expected

+ Comparison {}
- Comparison {
-   status: 500
- }
    at processTicksAndRejections (internal/process/task_queues.js:95:5)
    at Context. (test/test.awsclient.ts:406:9)

[flaky-bot[bot]]

Closing as a duplicate of #1598