Fix compat override for TalkNet Aligner
# What does this PR do ?

Moves the override to `load_state_dict()` from TalkNet (which doesn't need it) to EncDecCTCModel for compatibility with the TalkNet Aligner checkpoint. Related ISSUE: https://github.com/NVIDIA/NeMo/issues/4015

This should be removed in 1.9.0 when the TalkNet Aligner model is deprecated.

**Collection**: TTS, ASR

**PR Type**:
- [ ] New Feature
- [x] Bugfix
- [ ] Documentation