[JENKINS-74068] Extract inline JavaScript from BuildMonitorView/configure-entries.jelly

[yaroslavafenkin]

https://issues.jenkins.io/browse/JENKINS-74068

Testing done

To make sure the affected code runs you need at least one folder with a job nested inside of it. Then the event handler can be triggered by checking the "Recurse in subfolders" checkbox on the build monitor view configuration page.

Before the change
After the change

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• Ensure that the pull request title represents the desired changelog entry
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[basil]

Thanks for the PR!