[JENKINS-74070] Remove inline script block in io/jenkins/plugins/gitlabbranchsource/GitLabSCMSource/config-detail.jelly

[basil]

Definitely the easiest CSP fix I have seen in this project. All of the code was commented out and thus can trivially be deleted. The code appears to have been commented out since it was originally checked in at commit 0a0471b.

Testing done

mvn clean verify
No manual testing, as this code was commented out all along.

Submitter checklist

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• Ensure that the pull request title represents the desired changelog entry
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