Leverage integration testing with Jest

There are recurring regressions happening and I think that we can update some parts of our testing strategy to catch more of these. In parallel we should also rethink how me measure quality specs as part of feature delivery. I tend to see spec files that have many tests, but often they don't tell conclusive stories and are meaningless when it comes to protecting our codebase.

e.g https://gitlab.com/gitlab-org/gitlab/-/blob/master/spec/javascripts/ide/components/file_row_extra_spec.js

As part of this issue I will discuss with @meks and @at.ramya on how to form a strategy on improving status quo.