Skip _cudnn_rnn_backward in codegen check (#61386)
Summary:
Fixes internal test failure encountered internally
For context see: https://github.com/pytorch/pytorch/issues/60426
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61386
Reviewed By: malfet
Differential Revision: D29601031
Pulled By: soulitzer
fbshipit-source-id: 3592ca45a01e7bbaa804ab5404338191154f0fbc
