test: unflake lru-disk-eviction on Windows (#90465)
```
FAIL Turbopack test/unit/image-optimizer/lru-disk-eviction.test.ts
LRU disk eviction
√ should evict oldest entries on initialization (133 ms)
√ should evict old entries when new entries are set (124 ms)
× should promote entries on get() to prevent eviction (8 ms)
√ should return the same LRU instance on subsequent calls (1 ms)
√ should deduplicate concurrent init calls (2 ms)
√ should handle empty cache directory (2 ms)
√ should handle non-existent cache directory (2 ms)
● LRU disk eviction › should promote entries on get() to prevent eviction
EPERM: operation not permitted, rmdir 'C:\Users\ADMINI~1\AppData\Local\Temp\next-lru-test-dOXRaF\y'
```
