SOLR-15203: remove deprecated jwk url

[epugh]

Description

Removing deprecated parameter.

Solution

Just some clean up, documented in the upgrade notes.

Tests

n/a

Checklist

Please review the following and check all that apply:

• [X ] I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• [ X] I have created a Jira issue and added the issue ID to my pull request title.
• [ X] I have given Solr maintainers access to contribute to my PR branch. (optional but recommended)
• [ X] I have developed this patch against the main branch.
• [ X] I have run ./gradlew check.
• I have added tests for my changes.
• [X ] I have added documentation for the Reference Guide

[janhoy]

Hi Eric. Please delete the branch after merging. And please consider putting future feature branches in your privte fork instead of in the shared repo :)