3.0 Deprecation Warning: Deprecate fallback spaCy model

Background This warning was found in:

• rasa.nlu.utils.spacy_utils.py:L140

"f""SpaCy model is not properly configured! ""
 f""Please add a `model` property to `SpacyNLP`. ""
f""Will use '{spacy_model_name}' as a fallback spaCy model. ""
f""This fallback will be deprecated in Rasa 3.0"""

Definition of Done

• resolve warning in 3.0 version
• Removed all uses of _check_model_fallback in favour of using directly model from config. Here I assume we don’t have to do any checking on model – if a Spacy model with that name doesn’t exist, then Spacy will raise an error? 🤔 Currently, we do checking but it requires hard-coding all possible Spacy model names, which then leads to issues like Support spaCy 3.1 #9068 which are just about updating that hard-coded list afaics.
• Remove tests for _check_model_fallback
• Removed the references in the docs

[koaning]

The PR is ready and no longer a work in progress. The upgrade to spaCy 3.1 will be a separate PR.

[TyDunn]

@koaning Thanks for picking this up. This will be blocking the architecture revamp. Once 2.8 is released early next week, if you have not completed this issue (probably have two weeks), Enable might reach out about taking it over