[JENKINS-73892] un-inline script in config.jelly and fix existing behavior

[shlomomdahan]

JENKINS-73892

Default behavior was broken, so I fixed it along with the CSP issue by adding the relevant class name to the element.

Broken default behavior: https://www.loom.com/share/d1ceff4bfb4a40748c4dc36415d2a18e

CSP_nonRestrictive: https://www.loom.com/share/9fac40c2ecf14c9496dad64cd56205aa

CSP_restrictive: https://www.loom.com/share/f934c52aa3644a9b9169f72579cb13fd

Testing done

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.88%. Comparing base (c98df34) to head (45809bf).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #427   +/-   ##
=========================================
  Coverage     71.88%   71.88%           
  Complexity      206      206           
=========================================
  Files            16       16           
  Lines           900      900           
  Branches        126      126           
=========================================
  Hits            647      647           
  Misses          186      186           
  Partials         67       67           

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[jtnord]

Thanks @shlomomdahan