Update TestCase for new fixtures loading.
Review Request #14808 — Created Feb. 10, 2026 and submitted — Latest diff uploaded
Fixtures are now (primarily) loaded at class setup time rather than
per-test-case. This change updates Review Board's TestCase class to
handle that, and simplifies our handling of thetest_scmtools
fixture, which is not a real fixture file anymore but ends up triggering
loading of SCMTools from the registry.
Ran unit tests.