Fix Storybook visual issues due to CSF migration completion

This fixes a few issues that started happening due to the completion of the CSF migration:

• In some stories, not all of the components used were properly registered. This worked as long as storybook-readme was loaded in at least one story as it was globally registering all components. We had done a first pass at fixing this in !2642 (merged), but we apparently had misses some occurrences. More context in !2592 (comment 824702851).
• This moves the setConfigs call to the correct place to affect the stories. Having this call in the manager likely wasn't the right place. According to the docs, the manager is responsible for rendering the side controls, while the preview is for rendering the actual stories. The fact that the config was properly loaded until now was likely another side-effect of having storybook-readme loaded in some story.