[WIP] Annotate CodeQL warnings to suppress flags in test files

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Original prompt

Go to task 6150 in NuGet Gallery. I want to annotate codeQL warnings to suppress them because they are test files. More info here:

Problem description
We got more S360 CodeQL flags about credscan finding "secrets".

Solution
Make sure flagged locations are not actual secrets, annotate them so CodeQL ignores them going forward.

How can I annotate them in order to suppress the flags.

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