[W2V2 with LM] Fix decoder test with params
Author: sanchit-gandhi
Pull request: yes

# What does this PR do?

Fixes https://github.com/huggingface/transformers/pull/21226. This test started failing due to a PyPI update of pyctcdecode, which incorporated a number of bug fixes to the LM decode method (see https://github.com/kensho-technologies/pyctcdecode/issues/107#issuecomment-1400757049). 

This PR modifies the decoding params, such that the same outputs are obtained for pyctcdecode v0.4.0 and v0.5.0 (latest) - hence the test should pass irrespective of the package version while still verifying correctness of the outputs. The PR also adds tests for the LM and logit scores.

## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [ ] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#start-contributing-pull-requests),
      Pull Request section?
- [x] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
- [ ] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/main/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/main/docs#writing-source-documentation).
- [ ] Did you write any new necessary tests?


## Who can review?

Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
members/contributors who may be interested in your PR.

<!-- Your PR will be replied to more quickly if you can figure out the right person to tag with @

 If you know how to use git blame, that is the easiest way, otherwise, here is a rough guide of **who to tag**.
 Please tag fewer than 3 people.

Models:

- text models: @ArthurZucker and @younesbelkada
- vision models: @amyeroberts and @NielsRogge
- speech models: @sanchit-gandhi
- graph models: @clefourrier

Library:

- flax: @sanchit-gandhi
- generate: @gante
- pipelines: @Narsil
- tensorflow: @gante and @Rocketknight1
- tokenizers: @ArthurZucker
- trainer: @sgugger

Integrations:

- deepspeed: HF Trainer: @stas00, Accelerate: @pacman100
- ray/raytune: @richardliaw, @amogkam

Documentation: @sgugger, @stevhliu and @MKhalusova

HF projects:

- accelerate: [different repo](https://github.com/huggingface/accelerate)
- datasets: [different repo](https://github.com/huggingface/datasets)
- diffusers: [different repo](https://github.com/huggingface/diffusers)
- rust tokenizers: [different repo](https://github.com/huggingface/tokenizers)

Maintained examples (not research project or legacy):

- Flax: @sanchit-gandhi
- PyTorch: @sgugger
- TensorFlow: @Rocketknight1

 -->


Comments:
_The documentation is not available anymore as the PR was closed or merged._

Indeed the var names are a bit confusing @ydshieh! They follow the same convention throughout the test file, where `decoded_processor` refers to the LM outputs decoded by the HF **processor** class, and `decoded_decoder` refers to the LM outputs decoded by the pyctc **decoder** class.

I'll update these var names in a follow-up PR to make them a bit more intuitive 👍