fix: revert async e2e fixture to use time.sleep() for optimization target

The e2e test expects codeflash to detect and fix the intentional use of
blocking time.sleep() in an async function. Using asyncio.sleep() removes
the optimization opportunity and causes the CI job to fail.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: KRRT7

code_to_optimize/code_directories/async_e2e/main.py

@@ -1,18 +1,16 @@
+import time
 import asyncio
 
 
 async def retry_with_backoff(func, max_retries=3):
     if max_retries < 1:
         raise ValueError("max_retries must be at least 1")
     last_exception = None
-    _sleep = asyncio.sleep
     for attempt in range(max_retries):
         try:
             return await func()
         except Exception as e:
             last_exception = e
             if attempt < max_retries - 1:
-                delay = 0.0001 * attempt
-                if delay:
-                    await _sleep(delay)
+                time.sleep(0.0001 * attempt)
     raise last_exception