Fix high CPU usage because of author name autocomplete

[HoussemNasri]

Fix #9952
Fix #6967

Probably because of a deadlock while accessing AthorList#AUTHOR_CACHE but can't confirm...

Actually, this can't be a deadlock because there were no use of locks. It's a well known problem that cause non thread-safe Map implementations to get into an infinite loop if accessed concurrently.
https://dzone.com/articles/java-7-hashmap-vs

Mandatory checks

• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[HoussemNasri]

I created a new PR based on an upstream branch so the build gets uploaded to builds.jabref.org

[github-actions]

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[Siedlerchr]

seems like a possible solution

[Siedlerchr]

As the reports were positive, I am merging this

[HoussemNasri]

@Siedlerchr No changelog?

[Siedlerchr]

Yeah, we should probably add one. Can you do this in a follow up?