Reduce complexity of ee_mr_widget_options

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Close this issue

Context

(Follow up from !27120 (merged))

Description

When moving the ee_mr_widget_options_spec over to Jest, we noticed that this is a huge spec file and a lot of the individual specs are bumping into each other. We could try to just clean up the specs, but part of this is caused by a very large and complex component.

Let's clean up the component and the specs! Here's some ideas:

• Move the call to MRWidgetService.fetchInitialData() out of the component and into app/assets/javascripts/vue_merge_request_widget/index.js. This way we won't be managing state and asynchronous events in our component tests.
• Instead of having the EE MrWidgetOptions component extend the CE one, let's see if we can have it compose the CE one 🤔