tests/functional: enable debug logging for QEMUMachine

tests/functional: enable debug logging for QEMUMachine

Set the 'qemu.machine' logger to 'DEBUG' level, to ensure we see log
messages related to the QEMUMachine class. Most importantly this
ensures we capture the full QEMU command line args for instances we
spawn.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20241121154218.1423005-12-berrange@redhat.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20241121165806.476008-12-alex.bennee@linaro.org>