tests/functional: put QEMUMachine logs in testcase log directory

tests/functional: put QEMUMachine logs in testcase log directory

We are not passing the 'log_dir' parameter to QEMUMachine, so the
QEMU stdout/err logs are being placed in a temp directory and thus
deleted after execution. This makes them inaccessible as gitlab
CI artifacts.

Pass the testcase log directory path into QEMUMachine to make the
logs persistent.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20241121154218.1423005-10-berrange@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20241121165806.476008-10-alex.bennee@linaro.org>