Fix bug for T5x to PyTorch convert script with varying encoder and decoder layers (#27448)
* Fix bug in handling varying encoder and decoder layers
This commit resolves an issue where the script failed to convert T5x models to PyTorch models when the number of decoder layers differed from the number of encoder layers. I've addressed this issue by passing an additional 'num_decoder_layers' parameter to the relevant function.
* Fix bug in handling varying encoder and decoder layers