Investigate slow jest tests + fill test gaps
## Summary
Some of the jests test under analytics/cycle_analytics occasionally timeout when running locally, particularly some tests in `base_spec` and `custom_stage_form_spec`.
## Improvements
We should investigate if these can be easily fixed, additionally we should:
- [x] Make more use of shallow rendering if available
- [x] Utilise snapshot tests where they make sense
- [x] Add the missing tests for the [`receiveCycleAnalyticsDataSuccess` action](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/68823)
- [x] ~~Add missing tests for: `ee/.../stage_nav_item.vue` - no data available, with / without stage median values etc~~ - [component has been removed](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/61431) with the updated stage table
- [x] Clean up mocked requests in `base_spec` as we might not need them now we check the requests in `actions_spec`
- [x] Fix todo by adding a test or [remove text](https://gitlab.com/gitlab-org/gitlab/-/blob/8647e53d82a4de2c3f3f38f64839c7c327c4aa00/ee/spec/features/analytics/cycle_analytics/cycle_analytics_spec.rb#L66) - There are existing controller tests to confirm this returns a 404 when the feature is disabled
- [ ] Drop [old cycle analytics fixtures](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/spec/frontend/analytics/cycle_analytics/mock_data.js#L15) and [rspec fixture](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/spec/frontend/fixtures/analytics.rb#L109)
- [x] Reduce some duplication in `ee/spec/features/analytics/cycle_analytics/cycle_analytics_spec.rb` - Specs were split into [multiple files + helpers](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/41236#note_409232096)
- [x] Check coverage
- [x] ~~[Remove `setUrlParams` mock and assert `historyPushState` receives correct params](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/23493#note_289552279)~~ - we no longer update URL params in the vuex actions, these occur via the [url-sync component](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/app/assets/javascripts/analytics/cycle_analytics/components/base.vue#L9) instead
- [x] Spy on api requests in vuex actions to ensure they are called with the correct parameters
## Risks
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Please list features that can break because of this refactoring and how you intend to solve that.
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## Involved components
* `ee/spec/frontend/analytics/cycle_analytics/**/*_spec.js`
* `ee/spec/features/analytics/cycle_analytics/cycle_analytics_spec.rb`
## Optional: Intended side effects
* Eliminate test timeouts
* Faster test execution
* Increased coverage
## Optional: Missing test coverage
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If you are aware of tests that need to be written or adjusted apart from unit tests for the changed components,
please list them here.
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epic
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