[JENKINS-74118] Remove inline onClick handlers in ScriptBuildStep/config.jelly

[shlomomdahan]

JENKINS-74118

Very similar to #30

There is an onClick Handler on the Add Argument button however it looks like the functionality was previously removed. I removed it and it does not affect the functionality at all. relevant commit

Testing done

After Changes:

Screen.Recording.2024-12-05.at.7.52.02.PM.mov

1. Go to Manage Jenkins -> Managed Files -> Add new config file
2. Select 'Managed Script File` -> Save and submit.
3. Create Freestyle Project -> In Build Steps select: Execute Managed Script
4. Select the script create above -> Here you will see the code changed:
   i. view selected file
   ii. Add Argument

Submitter checklist

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