BI-3069: Observation unit search by studyDbId incorrectly filters results using external reference ID.

[humsika]

Description

Story: BI-3069

Observation units were not being returned when filtering by studyDbId.

The search correctly found the observation units using the real studyDbId, but an additional filter compared that ID with the study’s external reference ID. Since these IDs are different, the matching observation units were removed from the response.

This change removes the unnecessary external-reference filter and uses the BrAPI studyDbId search result directly. The existing germplasm filter remains unchanged.

Dependencies

bi-web: epic/BI-2862
bi-api: feature/BI-3069
brapi-Java-ProdServer: epic/BI-2862

Testing

General experiment and observation unit regression, with focus on:

• Experiments & Observations page
• Opening an experiment dataset with multiple environments
• Confirming experimental units and their environments display correctly

Run the full bi-api test suite. All tests are expected to pass.

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