Fix remediation output for health tests for certs

[arudell]

This pull request enhances the certificate validation logic in the SDN diagnostic health module by improving how certificate details are collected and reported in several health test functions. The main improvements include standardizing the way certificate properties are gathered and ensuring that results are consistently stored for reporting.

Certificate details collection and reporting:

• Refactored Test-SdnCertificateExpired and Test-SdnCertificateMultiple to accumulate certificate details into an array and assign them to Properties at the end of execution, ensuring consistent and structured reporting of affected certificates. [1] [2] [3] [4] [5]
• In Test-SdnNonSelfSignedCertificateInTrustedRootStore, introduced a variable to collect certificate details and improved the process of adding certificate information to the result array.

Certificate selection logic:

• Enhanced logic in Test-SdnCertificateMultiple to prioritize certificates issued by AzureStackCertificationAuthority when determining which certificate to keep, and improved the remediation message formatting.

Change type

• Bug fix (non-breaking change)
• Code style update (formatting, local variables)
• New Feature (non-breaking change that adds new functionality without impacting existing)
• Breaking change (fix or feature that may cause functionality impact)
• Other

Checklist:

• My code follows the style and contribution guidelines of this project.
• I have tested and validated my code changes.