Migrate 1010ez disability rating code to BGS

[lihanli]

Summary

migrate from EVSS disability rating api to BGS disability rating api because the EVSS api is being deprecated. remove prefill_compensation_type code because the frontend is always sending the compensation type now and it doesn't need to be filled by the backend.

• (Which team do you work for, does your team own the maintainence of this component?)
  i work for the 1010 team, we own this code

Related issue(s)

department-of-veterans-affairs/va.gov-team#56673

Testing done

tested with unit tests

What areas of the site does it impact?

1010ez form

Acceptance criteria

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• Documentation has been updated (link to documentation)
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs

[ryan-mcneil]

LGTM!