Code review comment for ~medicalwei/plainbox-provider-checkbox:fix-audio-test

I am not able to reproduce the original bug because I returned the machine where the bug occurs.

It seems the reboot is triggered by the fact that it has NVIDIA dGPU, and dGPU switching was the reboot criteria.

However, by manually doing `sudo -s` to root then `sudo -s -u user` to user account I can recreate the symptom:

--------------[ Running job 1 / 2. Estimated time left: 0:00:11 ]---------------
-------------------------[ audio/detect_sinks_sources ]-------------------------
ID: com.canonical.certification::audio/detect_sinks_sources
Category: com.canonical.plainbox::audio
... 8< -------------------------------------------------------------------------
Connection failure: Connection refused
pa_context_connect() failed: Connection refused
No available sources found
Connection failure: Connection refused
pa_context_connect() failed: Connection refused
No available sinks found
------------------------------------------------------------------------- >8 ---
Outcome: job failed
--------------[ Running job 2 / 2. Estimated time left: 0:00:10 ]---------------
--------------------[ audio/alsa_record_playback_automated ]--------------------
ID: com.canonical.certification::audio/alsa_record_playback_automated
Category: com.canonical.plainbox::audio
Job cannot be started because:
 - required dependency 'com.canonical.certification::audio/detect_sinks_sources' has failed
Outcome: job cannot be started

then at the same environment running the audio test with the patch, the audio tests are passed:

--------------[ Running job 2 / 3. Estimated time left: 0:00:11 ]---------------
-------------------------[ audio/detect_sinks_sources ]-------------------------
ID: com.canonical.certification::audio/detect_sinks_sources
Category: com.canonical.plainbox::audio
... 8< -------------------------------------------------------------------------
5alsa_input.pci-0000_00_1f.3-platform-skl_hda_dsp_generic.HiFi__hw_sofhdadsp__sourcemodule-alsa-card.cs16le 2ch 48000HzSUSPENDED
6alsa_input.pci-0000_00_1f.3-platform-skl_hda_dsp_generic.HiFi__hw_sofhdadsp_6__sourcemodule-alsa-card.cs16le 2ch 48000HzSUSPENDED
1alsa_output.pci-0000_00_1f.3-platform-skl_hda_dsp_generic.HiFi__hw_sofhdadsp_5__sinkmodule-alsa-card.cs16le 2ch 48000HzSUSPENDED
2alsa_output.pci-0000_00_1f.3-platform-skl_hda_dsp_generic.HiFi__hw_sofhdadsp_4__sinkmodule-alsa-card.cs16le 2ch 48000HzSUSPENDED
3alsa_output.pci-0000_00_1f.3-platform-skl_hda_dsp_generic.HiFi__hw_sofhdadsp_3__sinkmodule-alsa-card.cs16le 2ch 48000HzSUSPENDED
4alsa_output.pci-0000_00_1f.3-platform-skl_hda_dsp_generic.HiFi__hw_sofhdadsp__sinkmodule-alsa-card.cs16le 2ch 48000HzSUSPENDED
------------------------------------------------------------------------- >8 ---
Outcome: job passed
--------------[ Running job 3 / 3. Estimated time left: 0:00:10 ]---------------
--------------------[ audio/alsa_record_playback_automated ]--------------------
ID: com.canonical.certification::audio/alsa_record_playback_automated
Category: com.canonical.plainbox::audio
... 8< -------------------------------------------------------------------------
INFO:root:Using PulseAudio identifier 5 (alsa_input.pci-0000_00_1f.3-platform-skl_hda_dsp_generic.HiFi__hw_sofhdadsp__source) for input
INFO:root:Using PulseAudio identifier 1 (alsa_output.pci-0000_00_1f.3-platform-skl_hda_dsp_generic.HiFi__hw_sofhdadsp_5__sink) for output
INFO:root:Player: Starting
INFO:root:Recorder: Starting
INFO:root:Sampling complete, ending process
INFO:root:Player: Stopping
INFO:root:Recorder: Stopping
INFO:root:PASS: Test frequency of 5035 in band (4995.70, 5081.84) which contains a magnitude peak
------------------------------------------------------------------------- >8 ---
Outcome: job passed