Revert "Using Pseudo Function to get Service URL Domain (#6632)"

[himani2411]

Description of changes

This reverts commit 28330be.

Tests

• test_iam_roles and test_ad_integration in isolated regions passed with this change

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[gmarciani]

Why not applying the same approach we did for the other template?

Service: !If [ GovCloud, 'ec2.amazonaws-us-gov.com', !If [ China, 'ec2.amazonaws.cn', 'ec2.amazonaws.com']]

[himani2411]

This was something that I reverted so i prefer to revert to the original value that was existing instead of changing it now and re-testing it again in isolated regions.

I have already created a backlog task for deep diving on why we should keep the SP at all especially in isolated regions.