feat: make displayName field optional during registration

[zly199]

What type of PR is this?

/kind feature

What this PR does / why we need it:
This PR adds the feature to make the name field optional during registration. This improves the user experience by allowing flexibility in the registration process.

Which issue(s) this PR fixes:

Fixes #7066

Special notes for your reviewer:
Please focus on the validation logic for optional fields and ensure it aligns with existing registration requirements.

Does this PR introduce a user-facing change?

release
复制代码
The name field in the registration form is now optional, enhancing flexibility during user si

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