Legal API - fix broken unit tests(warning services)

Broken unit tests will need to be updated such that they work and pass again.

Some of this work will involve updating the unit tests to work according with the alternate name model updates. In particular, SPs will be represented as alternate name entries while other businesses will be represented as legal entity entries.

Reference previous legal name unit test fix PRs as a reference.

For info around setting up dev environment for legal name work and also documentation around legal name work, ping Argus for documentation.

**TODOs**
- [ ] Do work in `feature-legal-name` branch
- [ ] Fix broken unit test in test_firms.py
- [ ] Update unit tests so it tests alternate names too where applicable
- [ ] There are a bunch of TODOs left over in the tests found in test_firms.py. The tests will need to be updated to work with alternate names. Here is one example [lear/legal-api/tests/unit/services/warnings/business/business_checks/test_firms.py at 027af43fdc5fdc8938fc82d3296bd86db3c59dce · bcgov/lear](https://github.com/bcgov/lear/blob/027af43fdc5fdc8938fc82d3296bd86db3c59dce/legal-api/tests/unit/services/warnings/business/business_checks/test_firms.py#L561-L566)
- [ ] Address commented out `test_check_completing_party_for_filing` test in `test_firms.py` and get it passing
- [ ] Verify updated tests pass in business API CI