configure principal claim name for oauth2

[mshima]

related to #24374

---

Please make sure the below checklist is followed for Pull Requests.

• All continuous integration tests are green
• Tests are added where necessary
• The JDL part is updated if necessary
• jhipster-online is updated if necessary
• Documentation is added/updated where necessary
• Coding Rules & Commit Guidelines as per our CONTRIBUTING.md document are followed

When you are still working on the PR, consider converting it to Draft (below reviewers) and adding skip-ci label, you can still see CI build result at your branch.

[mshima]

@mraible I will let you test with your existing application.

[mraible]

@mshima I tested this, and it does not fix the issue. I also tried using preferred_username since that's the spelling of the official claim.

[mraible]

I can confirm that this now works with Spring MVC. I did not test it with Spring WebFlux.

[mraible]

I created a new project with WebFlux and searched for authentication.name. Since there are no instances, I think we should merge this.