Fix test isolation in Flask app database tests

[adamtheturtle]

Summary

Reset TARGET_MANAGER state between tests by cleaning up cloud and VuMark databases in the autouse fixture. This fixes the leaky test issue where the module-level singleton was persisting state across tests, which required workaround keys ("v1", "v2", "v3" instead of "1", "2", "3") in test_duplicate_vumark_keys.

The fix reuses the public API (remove_cloud_database/remove_vumark_database) to clean up after each test, ensuring proper test isolation.

Changes

• Import TARGET_MANAGER in test_flask_app_usage.py
• Add cleanup code in the autouse fixture to remove all databases after each test
• Revert test keys from "v1"/"v2"/"v3" back to "1"/"2"/"3" since the underlying test leakiness is now fixed

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Note

Low Risk
Test-only changes that improve isolation by cleaning up shared singleton state; low risk aside from potential flakiness if cleanup interacts with concurrent tests.

Overview
Ensures tests/mock_vws/test_flask_app_usage.py no longer leaks state between tests by importing the singleton TARGET_MANAGER and clearing all cloud and VuMark databases in the autouse fixture teardown via remove_cloud_database/remove_vumark_database.

Updates the duplicate VuMark key test to use simple key values again ("1"/"2"/"3") now that prior test-created databases are reliably cleaned up.

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