feat(tests): Replaced usage of toBeTruthy with toBeDefined in item_title_spec.js

What does this MR do and why?

• This MR replaces the usage of toBeTruthy with toBeDefined
• This MR fixes #369825 (closed)

Screenshots or screen recordings

How to set up and validate locally

1. yarn
2. yarn jest spec/frontend/work_items/components/item_title_spec.js

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.