stay compatible for PCT

[mawinter69]

PCT leads to a mixture of plugin version and test-harness version. So the test will use the old newSource but the plugin expects value for the checkUrl parameter.

This change will stay with newSource as parameter but still removes the inline javascript.

fixes the problems with updating the jenkins/bom as mentioned in #2551

Your checklist for this pull request

🚨 Please review the guidelines for contributing to this repository.

• [x] Make sure you are requesting to pull a topic/feature/bugfix branch (right side) and not your master branch!
• [x] Ensure that the pull request title represents the desired changelog entry
• [x] Please describe what you did
• [ ] Link to relevant issues in GitHub or in Jenkins JIRA
• [ ] Link to relevant pull requests, esp. upstream and downstream changes
• [ ] Did you provide a test-case? That demonstrates feature works or fixes the issue.

[basil]

Many thanks @mawinter69! Keeping PCT clean is of great importance for me as I land the EE 9 project in the coming weeks, so this is highly appreciated.