Viewing another user's batch change as a non-admin user no longer works

Created by: LawnGnome

This broke Batch Changes, which live under the user's namespace. Non-admin users can no longer view the user account's subpages after this change. Example URL: https://sourcegraph.test:3443/users/eseliger/batch-changes/hello-world

Originally posted by @eseliger in https://github.com/sourcegraph/sourcegraph/issues/25528#issuecomment-942746985