Add missing Amazon provider unit tests

[fat-catTW]

Summary

Add dedicated unit tests for several Amazon provider modules that were listed in OVERLOOKED_TESTS.

This covers:

• AWS auth manager login response datamodel
• AWS executor base config keys
• AWS Lambda executor utils
• AWS Batch executor config

The covered files are removed from OVERLOOKED_TESTS.

Note: After review, this PR now only adds tests for BaseConfigKeys iteration behavior and AWS Batch unsupported submit_job_kwargs validation.

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---

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[o-nikolas]

I saw that you had over 15 PRs submitted and this work seems pretty sloppy. I'm not going to close this yet, but do take these changes seriously. It takes a lot of our time to review these. Don't make changes like these just to say you had PRs merged into Apache Airflow.

[fat-catTW]

Thank you for the honest feedback, and I’m sorry for the extra review burden this caused.

I take the reviews seriously and really appreciate the time maintainers spend reviewing contributions.
For context, those PRs were opened over a longer period, from July to September, and most of them were closed recently because of the new policy limiting contributors to 5 open PRs.

I understand that quality matters more than quantity.

[fat-catTW]

@o-nikolas
This PR has been open for a while. Could you take another look when you have a chance? Thanks a lot!