feat: migrate performance endpoints to Insights Snowflake

[santhosh-apphelix-2u]

Description

This PR completes the last group of the Insights Snowflake API migration by moving the performance endpoints behind the global Snowflake Waffle flag.

Migrated endpoints:

• GET /api/v1/courses/{course_id}/problems/
• GET /api/v1/problems/{problem_id}/answer_distribution/

When insights_snowflake_enabled is enabled, these endpoints read from Snowflake. When the flag is disabled, they continue using the existing Aurora flow.

Changes

• Added Snowflake query helpers for performance data using PROBLEM_ANSWER_DISTRIBUTION.
• Added mappers to keep the API response shape same as the existing Aurora response.
• Wired the performance views to use Snowflake only when the global flag is enabled.
• Preserved existing answer distribution consolidation and serializer behavior.
• Added tests for Snowflake query building, mapper output, service wiring, Aurora fallback, and Snowflake routing.

Notes

This is the final planned API migration PR for LP-1002. Out-of-scope legacy endpoints like problems_and_tags, grade_distribution, and sequential_open_distribution are unchanged.

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
analytics_data_api/insights_snowflake
service.py
analytics_data_api/insights_snowflake/mappers
performance.py					21, 28, 35, 52, 55
analytics_data_api/insights_snowflake/queries
performance.py
analytics_data_api/tests
test_insights_snowflake.py
analytics_data_api/v0/tests/views
test_courses.py
test_problems.py
analytics_data_api/v0/views
courses.py
problems.py
Project Total

This report was generated by python-coverage-comment-action