Refactor Camunda registration options + drop RJSF

[sergei-maertens]

No ticket, follow up on #4806

Changes

• Removed wrappers around RJSF from Camunda registration options, otherwise it's left untouched
• Removed vendor workarounds
• Removed RJSF dependency

Checklist

Check off the items that are completed or not relevant.

• Impact on features

  • Checked copying a form
  • Checked import/export of a form
  • Config checks in the configuration overview admin page
  • Problem detection in the admin email digest is handled

• Release management

  • I have labelled the PR as "needs-backport" accordingly

• I have updated the translations assets (you do NOT need to provide translations)

  • Ran ./bin/makemessages_js.sh
  • Ran ./bin/compilemessages_js.sh

• Commit hygiene

  • Commit messages refer to the relevant Github issue
  • Commit messages explain the "why" of change, not the how

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.55%. Comparing base (b96d2ae) to head (ef6cac1).
Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4807   +/-   ##
=======================================
  Coverage   96.55%   96.55%           
=======================================
  Files         748      748           
  Lines       25423    25423           
  Branches     3362     3362           
=======================================
  Hits        24548    24548           
  Misses        610      610           
  Partials      265      265           

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