Investigate yaml schema validation

[wochinge]

Description of Problem:
When we read YAML training data files, we validate them against a schema. This is currently taking a lot of time. Skipping this step e.g. brings down the training data reading times from 18 minutes to 8 minutes.

Overview of the Solution:

• is there a faster library?
• Can we accelerate our current library?
• Should we add a flag to the CI to disable the schema validation?

Definition of Done:

• Propose next steps to speed up the YAML schema validation

[wochinge]

related #7977

We should also double check if the schema extension here is needed or can be accelerated

[joejuzl]

See: https://json-schema-everywhere.github.io/yaml#:~:text=While%20YAML%20has%20advanced%20features,supported%20choice%20for%20YAML%20validation.

[gausie]

We should consider using jsonschema (and making the schemas public)

[alwx]

We decided to drop this one because the performance is good already and because we have more important stuff to work on.