re-add invalid email cert test cases

[havetisyan]

Description

after golang developers introduced the strict domain checks in the 1.25.2 release, it caused way too production incidents so they actually rolled back that change and implemented a different one.

From the 1.25.3 release:

This release addresses breakage caused by a security patch included in Go 1.25.2
and 1.24.8, which enforced overly restrictive validation on the parsing of X.509
certificates. We've removed those restrictions while maintaining the security
fix that the initial release addressed.
We apologize for any issues this may have caused.

So we're adding back our test cases with certs with invalid email address

Contribution Checklist:

• The pull request does not introduce any breaking changes
• I have read the contribution guidelines.
• Create an issue and link to the pull request.

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[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request restores test cases that were temporarily removed due to a breaking change in Go's X.509 certificate parsing. The Go team has since addressed the issue, making these test cases relevant again. The changes primarily involve re-introducing test cases with certificates containing invalid email addresses to ensure continued compatibility.

Highlights

• Reintroduction of Test Cases: This PR re-adds test cases that were previously removed due to overly strict domain checks in Go 1.25.2. These checks have since been rolled back in Go 1.25.3.
• Invalid Email Certificates: The test cases being re-added involve certificates with invalid email addresses, which are now valid again due to the Go rollback.
• Impact of Go 1.25.2: Go 1.25.2 introduced strict domain checks that caused production incidents, leading to a rollback and a new implementation in Go 1.25.3.

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[gemini-code-assist]

Code Review

This pull request re-introduces test cases for X.509 certificates with invalid email addresses, following a relaxation of validation rules in a dependency. The changes correctly add a test case to TestExtractInstanceIdValid to verify that instance ID extraction remains functional, and another to TestExtractServicePrincipalInValid to ensure principal extraction fails as expected for role certificates with invalid emails. The additions are logical and enhance test coverage appropriately.