Fix seed for recomputed Dropout (#19715)
### Fix seed for recomputed Dropout
If Dropout node is recomputed in the backward, we should make sure its
execution is same as the run in the forward.
If we don't set seed attribute, then this cannot be guaranteed.
Add ` export ORTMODULE_MEMORY_OPT_LEVEL=2` to enabled per layer
recompute with compromised recomputable subgraphs.
