Populate compile_time_autotune_time_us (#143104)

Summary:
See testing in attached diff

X-link: pytorch/pytorch#143104
Approved by: https://github.com/ezyang

Reviewed By: clee2000

Differential Revision: D67128210

Pulled By: masnesral

fbshipit-source-id: 5c7f5f98db7f4768127d61e7bcefef39b51a064c

userbenchmark/dynamo/dynamobench/_dynamo/utils.py

@@ -881,6 +881,7 @@ class CompilationMetrics:
     cuda_version: Optional[str] = None
     triton_version: Optional[str] = None
     feature_usage: Optional[dict[str, bool]] = None
+    compile_time_autotune_time_us: Optional[int] = None
 
 
 DEFAULT_COMPILATION_METRICS_LIMIT = 64