test: simplify test file mocking patterns (#8320)

Simplifies test mocking patterns across multiple test files.

- Removes redundant `vi.hoisted()` calls
- Cleans up mock implementations
- Removes unused imports and variables

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8320-test-simplify-test-file-mocking-patterns-2f46d73d36508150981bd8ecb99a6a11)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: GitHub Action <action@github.com>

src/renderer/core/thumbnail/useWorkflowThumbnail.test.ts

@@ -3,6 +3,9 @@ import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import type { ComfyWorkflow } from '@/platform/workflow/management/stores/workflowStore'
 import { useWorkflowStore } from '@/platform/workflow/management/stores/workflowStore'
+import { createGraphThumbnail } from '@/renderer/core/thumbnail/graphThumbnailRenderer'
+import { useWorkflowThumbnail } from '@/renderer/core/thumbnail/useWorkflowThumbnail'
+import { api } from '@/scripts/api'
 
 vi.mock('@/renderer/core/thumbnail/graphThumbnailRenderer', () => ({
   createGraphThumbnail: vi.fn()
@@ -19,12 +22,6 @@ vi.mock('@/scripts/api', () => ({
   }
 }))
 
-const { useWorkflowThumbnail } =
-  await import('@/renderer/core/thumbnail/useWorkflowThumbnail')
-const { createGraphThumbnail } =
-  await import('@/renderer/core/thumbnail/graphThumbnailRenderer')
-const { api } = await import('@/scripts/api')
-
 describe('useWorkflowThumbnail', () => {
   let workflowStore: ReturnType<typeof useWorkflowStore>