Make summarize_perf.py work with perf-compare (#99095)
[perf-compare](https://github.com/pytorch/pytorch/actions/workflows/inductor-perf-compare.yml) has a different structure than that of the nightlies.
For these files, the script now generates:
```
# cuda float32 training performance results
## Geometric mean speedup
huggingface timm_models torchbench
-------- ------------- ------------- ------------
inductor 1.46 1.4 1.17
## Mean compilation time
huggingface timm_models torchbench
-------- ------------- ------------- ------------
inductor 57.85 97.63 60.18
## Peak memory compression ratio
huggingface timm_models torchbench
-------- ------------- ------------- ------------
inductor 1.06 1.01 0.83
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/99095
Approved by: https://github.com/ezyang
