🐛 BUG: Vitest `__mocks__` not working when using `@cloudflare/vitest-pool-workers`

### Which Cloudflare product(s) does this pertain to?

Workers Vitest Integration

### What versions are you using?

2.1.8 [vitest], 0.5.40 [@cloudflare/vitest-pool-workers]

### What operating system and version are you using?

macIS Sequoia 15.1.1

### Please provide a link to a minimal reproduction

https://github.com/saitolume/workers-sdk-bug-report

### Describe the Bug

When using `@cloudflare/vitest-pool-workers`, the mocks defined in Vitest's `__mocks__` directory do not work as expected.

- Expected behavior:
Modules defined in the `__mocks__` directory should automatically be used as mocks.
- Actual behavior:
When using `@cloudflare/vitest-pool-workers`, the modules in `__mocks__` are not applied. Instead, Vitest's default mocking behavior is used.

### Please provide any relevant error logs

```
pnpm run test:fail

> @ test:fail /workers-sdk-bug-report
> vitest run --config vitest.fail.config.ts

RUN v2.1.8 /workers-sdk-bug-report

[vpw:inf] Starting isolated runtimes for vitest.fail.config.ts...
❯ index.test.ts (1)
× uuid

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ Failed Tests 1⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

FAIL index.test.ts > uuid
AssertionError: expected undefined to be 'expected' // Object.is equality

- Expected:
"expected"

+ Received:
undefined

❯ index.test.ts:7:16
5|
6| test('uuid', () => {
7| expect(v4()).toBe('expected')
| ^
8| })
9|

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ [1/1]⎯

Test Files 1 failed (1)
Tests 1 failed (1)
Start at 00:51:16
Duration 1.04s (transform 10ms, setup 0ms, collect 25ms, tests 6ms, environment 1ms, prepare 107ms)

[vpw:dbg] Shutting down runtimes...
 ELIFECYCLE  Command failed with exit code 1.
```