fix: prevent site storybook tests from hanging after completion (#23936)

The vitest process hung after all 2132 story tests passed because
leftover refetchInterval polls kept the Node.js event loop alive.
Components that set per-query refetchInterval override the
QueryClient default, causing HTTP requests through vite's proxy
to localhost:3000 (no backend) that never resolve cleanly.

Three fixes:

- preview.tsx: disable all automatic refetching defaults and cancel
  in-flight queries on story unmount via useEffect cleanup
- storybook.tsx: save/restore the original window.WebSocket in the
  withWebSocket decorator, clear pending timers in close()
- vite.config.mts: add explicit testTimeout, hookTimeout, bail, and
  retry settings to the storybook vitest project

Also fix 5 story files that imported from @testing-library/react
instead of storybook/test.

site/src/modules/tasks/TasksSidebar/UserCombobox.stories.tsx

@@ -1,7 +1,6 @@
 import type { Meta, StoryObj } from "@storybook/react-vite";
-import { waitFor } from "@testing-library/react";
 import { useState } from "react";
-import { expect, spyOn, userEvent, within } from "storybook/test";
+import { expect, spyOn, userEvent, waitFor, within } from "storybook/test";
 import { API } from "#/api/api";
 import { MockUsers } from "#/pages/UsersPage/storybookData/users";
 import { MockUserOwner } from "#/testHelpers/entities";