[aot_autograd] only performance functionalization analysis pass once (#95992)
For a while now, we've been re-running our functionalization analysis pass twice - once for get metadata when dedup'ing, and an entire second time during aot_dispatch_base/autograd.
This should also probably speed up compile times pretty noticeably, since we're going from:
(a) inference-only trace case: 3 fw traces -> 2 fw traces
(b) autograd trace case: 2 fw traces + 1 joint trace -> 1 fw trace + 1 joint trace
Pull Request resolved: https://github.com/pytorch/pytorch/pull/95992
Approved by: https://github.com/ezyang
