tests: use new decorator to skip audio tests on whonix-gateway

It's faster as the test is skipped before calling setUp().

qubes/tests/integ/audio.py

@@ -34,6 +34,7 @@
 from qubes.tests.integ.vm_qrexec_gui import TC_00_AppVMMixin, in_qemu
 
 
+@qubes.tests.skipIfTemplate("whonix-g")
 class TC_00_AudioMixin(TC_00_AppVMMixin):
     def start_extra_vm_logging(self, vm):
         """Log user journal and .xsession-errors to the console to be
@@ -77,8 +78,6 @@ def wait_for_pulseaudio_startup(self, vm):
         self.loop.run_until_complete(asyncio.sleep(1))
 
     def prepare_audio_test(self, backend):
-        if "whonix-g" in self.template:
-            self.skipTest("whonix gateway have no audio")
         self.loop.run_until_complete(self.testvm1.start())
         self.start_extra_vm_logging(self.testvm1)
         pulseaudio_units = "pulseaudio.socket pulseaudio.service"