Parse JDK correctly in different formatted Jenkinsfile

[sridamul]

Now we can extract JDK values from Jenkinsfile that differs from the standard one.
Eg: https://github.com/jenkinsci/forensics-api-plugin/blob/main/Jenkinsfile

Testing done

Unit tests written

Submitter checklist

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