Culprit:
(1) - BuildTriggerStep/config.jelly#L47-L60
(2) - BuildTriggerStep/config.jelly#L30

Reproduction steps:

• Install Pipeline: Build Step or clone https://github.com/jenkinsci/pipeline-build-step-plugin and then mvn hpi:run
• Create a pipeline
• Check "This project is parameterized"
• Add a String parameter with random value
• Save
• Navigate to [JENKINS_INSTANCE]/pipeline-syntax/
• As "Sample Step" select "build: Build a job"
• Select your previously created pipeline in the "Project to Build" field

Screenshot attached about where the feature is displayed.

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

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