Sqlite test_export_sql: flaky due to hardcoded /tmp paths + no tearDown

[eduralph]

Summary

Sqlite.tests.test_sqlite.ExportSQLTestCase::test_export_sql is flaky in CI and has surfaced as a recurring T3 delta across 7+ Gramps Testbed bundles (issue_10415, issue_10628, issue_5516, issue_5965, issue_6793, issue_7344, issue_7832), in both the gramps60 and gramps61 matrix legs. The root cause appears to be hardcoded /tmp paths and no tearDown cleanup, which leaves state between runs and makes the test order-dependent.

Symptoms

• The test is consistently unrelated to any patch under review, yet it appears as a new T3 delta, triggering a NEEDS-HUMAN sign-off item every time
• The failure appears in both run-addon-unit-60.json and run-addon-unit-61.json matrix legs

Suggested fix

1. Replace any hardcoded /tmp path with tempfile.mkdtemp() (or tempfile.TemporaryDirectory) to get an isolated, unique directory per run
2. Add a tearDown (or addCleanup) to remove the temporary directory after each test, preventing state leakage between runs

Short-term mitigation

Until the test is fixed, add the test ID to known_failures in both engine/baselines/run-addon-unit-60.json and engine/baselines/run-addon-unit-61.json in the Gramps Testbed so it stops surfacing as an unexplained delta.

Context

Identified via cross-cycle Act review of the Gramps Testbed v2 PDCA harness (act-log 2026-06-27).