test_loader: Workaround pytest 8.2 regression
pytest 8.2 fails to execute an unittest based test suite if the class containing the tests does not define a runTest method, so dynamically define it in the TestCaseWithTransport class from breezy.
Staging instance, all changes can be removed at any time
pytest 8.2 fails to execute an unittest based test suite if the class containing the tests does not define a runTest method, so dynamically define it in the TestCaseWithTransport class from breezy.