Add test for Sorter strategy

[yashpal2104]

Testing done

• Add test for SorterStrategy class
• Refactor the onCanceledItem method to invoke item.isCancelled for test

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did

[yashpal2104]

@MarkEWaite do let me know about the changes I made. Are they viable or not

[MarkEWaite]

As a general pattern, most Jenkins plugin maintainers don't review draft pull requests. A pull request is usually marked as draft by the submitter because they are not ready for review.

Since you asked for my feedback, I checked the CI job. There is a spotbugs warning. You need to fix the spotbus warning before I'll spend time reviewing the pull request in any other way.