web: fix duplicate stories

Created by: valerybugakov

Context

Running yarn storybook on main shows a bunch of errors in the console about duplicate story keys and two identical web story groups. Also, the ordering of story groups is broken — wildcard is not the first item on the list despite our configuration.

Test plan

• Run yarn storybook and ensure that wildcard is the first story group in the sidebar.
• Run STORIES_GLOB=client/web/src/enterprise/insights/**/*.story.tsx yarn workspace @sourcegraph/storybook run start and ensure that there's only one web stories group.

Before	After

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.