[dynamo] Only rename a proxy once (#122060)
Improves `benchmarks/dynamo/microbenchmarks/dynamo_microbenchmarks.py`
from 3.9s to 2.7s.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/122060
Approved by: https://github.com/oulgen
ghstack dependencies: #122039, #122043, #122055, #122058
