Frontend: Use `client.mutate` calls for testing new branch caching in pipeline editor
Follow-up for !62872 (comment 601945939):
In this particular case I think this is a suitable way to handle triggering the client update for the specs, would could also call the mutation on the client directly but since this is just a mock I don't consider this to be blocking but rather ~"technical debt"
😄
Update the specs in ~/pipeline_editor/components/file-nav/branch_switcher_spec.js to use mutation calls instead of setting the data and refetching the query.
Edited by Mireya Andres