Culprit:
(1) - workflow/controller.jelly#L12

Reproduction steps:

• Install Pipeline: Stage View or clone https://github.com/jenkinsci/pipeline-stage-view-plugin and then mvn hpi:run
• Create a pipeline
• As pipeline script, use the "Hello World" sample
• Save
• Build it

Screenshot attached about where the feature is displayed.

Proposal
https://www.jenkins.io/doc/developer/security/csp/#inline-javascript-blocks

Testing notes
 - Ensure to reproduce the feature before any change
 - Ensure that you reproduce the feature after you have made the change