Reduce complexity of ee_mr_widget_options
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## Context
(Follow up from https://gitlab.com/gitlab-org/gitlab/-/merge_requests/27120)
## 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 :thinking:
issue