fix: update expected coverage lines for optimized async e2e code

The optimized code removes `import time`, shifting all function lines
up by 1. Update expected_lines from [10-20] to [9-19] to match.

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

Author: KRRT7

tests/scripts/end_to_end_test_async.py

@@ -13,7 +13,7 @@ def run_test(expected_improvement_pct: int) -> bool:
             CoverageExpectation(
                 function_name="retry_with_backoff",
                 expected_coverage=100.0,
-                expected_lines=[10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20],
+                expected_lines=[9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19],
             )
         ],
     )