Add server certificates and private keys for various test cases

[t4niwa]

Description

In Go 1.25.2, the verification of X.509 certificate SANs (Subject Alternative Names) has been made stricter.

Certificates like the following are now treated as invalid:

• Domain names with a trailing dot (.): Such as the Fully Qualified Domain Name (FQDN) format example.com.
• Domain names with empty labels: Such as .example.com or example..com
• Labels exceeding 63 characters: Long domain names that exceed DNS label limits
• Improperly formatted email addresses: rfc822Name formats that do not comply with RFC 5322

A unit test was added to maintain backward compatibility.

Type of change

• Bug fix
• New feature
• Refactoring (no functional changes, no api changes)
• Non-code changes (update documentation, pipeline, etc.)

Flags

• Breaks backward compatibility
• Requires a documentation update
• Has untestable code

Related issue/PR

Delete this section if there are no issues or pull requests that relate to this pull request.

• Fixes #issue
• Closes #PR

---

Checklist

• Followed the guidelines in the CONTRIBUTING document
• Added prefix [skip ci]/[ci skip]/[no ci]/[skip actions]/[actions skip] in the PR title if necessary
• Tested and linted the code
• Commented the code
• Made corresponding changes to the documentation
• Passed all pipeline checking

Checklist for maintainer

• Use Squash and merge
• Double-confirm the merge message has prefix [skip ci]/[ci skip]/[no ci]/[skip actions]/[actions skip]
• Delete the branch after merge