[Quant][PT2E]Make _fuse_conv_bn_ support graph capture by torch._dynamo.export (#107951)
**Summary**
The latest check-in https://github.com/pytorch/pytorch/commit/a0cfaf068887a608c00de4f5ceaf30242c6af720 for the conv-bn folding assumes the graph is captured by the new graph capture API `torch._export.capture_pre_autograd_graph`. Since we still need to use the original graph capture API `torch._dynamo_export` in 2.1 release. So, this check-in made negative impact to workloads' performance heavily. Made this PR to fix this issue by trying to make the conv-bn folding function workable with both new and original graph capture API.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/107951
Approved by: https://github.com/jgong5, https://github.com/jerryzh168
ghstack dependencies: #106836, #106838, #106958
