[TTS] Fix TTS recipes with PTL 2.0

[rlangman]

What does this PR do ?

Update TTS configs so they run with PTL 2.0

Collection: [TTS]

Changelog

• Replace ddp with ddp_find_unused_parameters_true for all vocoder recipes, otherwise it fails because there are unused parameters during the alternating generator and discriminator training steps.
• Update training_epoch_end() for AudioCodec to be compatible with new PTL interface.

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PR Type:

• New Feature
• Bugfix
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[redoctopus]

Thanks for fixing this! LGTM