add execution mode to the test name (#29284)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29284
as title
Test Plan:
```
buck run //caffe2/benchmarks/operator_benchmark/pt:add_test -- iterations 1 --ai_pep_format true
# ----------------------------------------
# PyTorch/Caffe2 Operator Micro-benchmarks
# ----------------------------------------
# Tag : short
# Benchmarking PyTorch: add
PyTorchObserver {"type": "PyTorch_add_M64_N64_K64_cpu_Eager", "metric": "latency", "unit": "ms", "value": "26.64516019518487"}
Reviewed By: hl475
Differential Revision: D18336980
fbshipit-source-id: 1f9d5147a56afeb68cd526a57f7375c5ec39efa4
