Fix issues where bi-generated exref id used instead of trialDbId in brapi endpoints

[jloux-brapi]

Description

Story: BI-2944

Matches to the submitted trialDbId to the trial ex ref were removed in favor of using the actual BrAPI trailDbId explicitly to resolve functionality mismatches.

This change further cements the notion that for all intents and purposes, expId=trialDbId.

Dependencies

• Use feature/BI-2861 branch of the prod server
• Use epic/BI-2862 branch of bi-web
• You may need to build the feature/BI-2861 branch of the brapi repo for bi-api to pick up the required changes.

Testing

Test the endpoints that were changed:

• http://localhost:8081/v1/programs/[insert program id]/brapi/v2/variables?trialDbId. For this endpoint, all test with param ?studyDbId, where this id is the environment database id, and should be the BI generated id, and should remain this way until the study cache is removed.
• http://localhost:8081/v1/programs/[insert program id]/brapi/v2/observationunits?trialDbId. For this endpoint ensure test uses the BrAPI trialDbId to get the observation units available, not the bi-generated exref id.

Checklist:

• I have performed a self-review of my own code
• I have tested my code and ensured it meets the acceptance criteria of the story
• I have create/modified unit and/or integration tests to cover this change or tests are not applicable
• I have commented my code, particularly in hard-to-understand areas
• I have either updated the source of truth or arranged for update with product owner if needed https://breedinginsight.atlassian.net/wiki/spaces/BI/pages/1559953409/Source+of+Truth