[Benchmarking] Migrate serving sweep CLI from argparse to cyclopts

Replace the hand-rolled argparse parser in sweep-benchmark-serving.py
with cyclopts, using `SweepServingBenchmarkConfig` directly as the CLI
model. Adds a `collect_gpu_stats `field to SweepServingBenchmarkConfig
and wires it through.

MODULAR_ORIG_COMMIT_REV_ID: bb5a4de312dd81111fb27f7ce21f81578a5b92de

Author: tzhenghao

max/python/max/benchmark/benchmark_shared/config.py

@@ -1007,6 +1007,12 @@ class SweepServingBenchmarkConfig(ServingBenchmarkConfig):
         },
     )
 
+    collect_gpu_stats: bool = Field(
+        default=True,
+        description="Enable GPU stats collection for serving benchmarks.",
+        json_schema_extra={"group": "Control Flags"},
+    )
+
     @classmethod
     def get_default_required_fields(cls) -> set[str]:
         """Get required fields for the sweep benchmark config."""