Auth API - update firm affiliation logic to work in sandbox

[argush3]

When a firm(corp_type_code = SP or GP) is created in the sandbox currently, the affiliation logic fails in prod auth api. It seems like other business types are fine from initial testing.

The issue appears to be that the auth api in prod fails for firm affiliations when it does the pass code validation in _validate_firms_party. Auth api is calling the prod legal api parties endpoint which fails because the business being affiliated only exists in sandbox.

To fix the issue, the firm passcode validation logic(_validate_firms_party) will need to be updated call the sandbox legal api parties endpoint when the POST affiliations call is called with the sandbox header(Environment-override: sandbox). A new config will need to be added for the sandbox legal api url.

[seeker25]

Already deployed to prod

[seeker25]

Reopen if needed