bug: failing unit tests after introduction of fips endpoints

[dayaffe]

Describe the bug

The following release to aws-models broke 2 of our unit tests in AWSIAM EndpointTests:
https://github.com/aws/aws-models/commit/74534ff18978911bf5ce693f105e261d3ee8f8bd

Breaks 28 and 29 here

Expected Behavior

Unit tests should pass so that our nightly model integration passes as well.

Current Behavior

Unit tests & model integration fails

Reproduction Steps

28:
host: "iam.eu-isoe-west-1.cloud.adc-e.uk" with region "eu-isoe-west-1" != host: "iam.amazonaws.com" with region "us-east-1"
29:
host: "iam.us-isof-south-1.csp.hci.ic.gov" with region "us-isof-south-1" != host: "iam.amazonaws.com" with region "us-east-1"

Possible Solution

No response

Additional Information/Context

No response

AWS SWIFT SDK version used

latest

Compiler and Version used

latest

Operating System and version

mac