test(gpu): make sleep/wake test memory util env-configurable (GMU)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Hejian Sang <sanghj0923@gmail.com>

Author: HJSang

test/runtime/test_sleep_wakeup_gpu.py

@@ -43,7 +43,7 @@ def main() -> None:
     engine = Engine(
         model=model,
         enable_memory_saver=True,
-        gpu_memory_utilization=0.1,
+        gpu_memory_utilization=float(os.environ.get("GMU", "0.1")),
         max_model_len=2048,
         trust_remote_code=True,
         log_level="info",