Inherit envvars more aggressively (bugfix)

[Hook25]

Description

The point of inheriting them from only DISPLAY having processes was to target user processes. This prioritizes them (as we do know the username) but still proceeds till we run out of options. Additionally this also calculates XDG_RUNTIME_DIR and DBUS_SESSION_BUS_ADDRESS always if it wasn't found anywhere to (try) to make the job start anyway with a sane-ish value

Resolved issues

Fixes: CHECKBOX-1990
Fixes: #2058

Documentation

N/A

Tests

Launch a container and define the XDG_RUNTIME_DIR envvar. After this PR the function will read it correctly, before it won't.

[codecov]

Codecov Report

❌ Patch coverage is 95.78059% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 51.90%. Comparing base (30f498f) to head (551d8e3).
⚠️ Report is 102 commits behind head on main.

Files with missing lines	Patch %	Lines
providers/base/bin/reboot_check_test.py	92.20%	2 Missing and 4 partials ⚠️
...ckbox-ng/plainbox/impl/session/remote_assistant.py	83.33%	1 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2067      +/-   ##
==========================================
+ Coverage   51.66%   51.90%   +0.24%     
==========================================
  Files         386      387       +1     
  Lines       41492    41679     +187     
  Branches     7711     7743      +32     
==========================================
+ Hits        21435    21635     +200     
+ Misses      19293    19275      -18     
- Partials      764      769       +5     

Flag	Coverage Δ
checkbox-ng	70.90% <83.33%> (+0.12%)	⬆️

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[fernando79513]

TYVM for this PR!
I think the strategy to inherit the envvars is much clearer now, and the detailed comments are appreciated.

Could you run the audio/alsa-playback in one of the DUTs that failed the test before to be sure that your change fixes the issue?

[LiaoU3]

Building snaps for testing.
https://github.com/canonical/checkbox/actions/runs/16824836263

[LiaoU3]

My sideload job

id: audio/alsa-playback
_summary: Playback works
_purpose:
 Check if sound is played through ALSA on the default output
_steps:
 1. Make sure speakers or headphones are connected to the device
 2. Commence the test
_verification:
 Did you hear the sound?
plugin: user-interact-verify
depends: audio/detect-playback-devices
environ: ALSA_CONFIG_PATH ALSADEVICE
flags: also-after-suspend
command:
 set -x
 echo "$XDG_RUNTIME_DIR"
 echo "$DBUS_SESSION_BUS_ADDRESS"
 alsa_test playback -d 5
category_id: com.canonical.plainbox::audio
estimated_duration: 10

It seems fixed on 202309-32029 with server 22.04

-----------------------------[ Running job 3 / 3 ]------------------------------
-------------------------------[ Playback works ]-------------------------------
ID: com.canonical.certification::audio/alsa-playback
Category: Audio tests
--------------------------------------------------------------------------------
Purpose:

Check if sound is played through ALSA on the default output

Steps:

1. Make sure speakers or headphones are connected to the device
2. Commence the test

Pick an action
    => press ENTER to continue
  c => add a comment
  s => skip this job
  q => save the session and quit
[csq]: 
+ echo /run/user/1000
+ echo unix:path=/run/user/1000/bus
+ alsa_test playback -d 5
/run/user/1000
unix:path=/run/user/1000/bus
ALSA lib conf.c:4016:(snd_config_hooks_call) function snd_config_hook_load_for_all_cards returned error: File exists
Failed to change volume: Master mixer not found.

It also seems fixed on 202412-36092 with server 24.04

-----------------------------[ Running job 3 / 3 ]------------------------------
-------------------------------[ Playback works ]-------------------------------
ID: com.canonical.certification::audio/alsa-playback
Category: Audio tests
--------------------------------------------------------------------------------
Purpose:

Check if sound is played through ALSA on the default output

Steps:

1. Make sure speakers or headphones are connected to the device
2. Commence the test

Pick an action
    => press ENTER to continue
  c => add a comment
  s => skip this job
  q => save the session and quit
[csq]: 
+ echo /run/user/1000
+ echo unix:path=/run/user/1000/bus
+ alsa_test playback -d 5
/run/user/1000
unix:path=/run/user/1000/bus
Verification:

Did you hear the sound?

Please decide what to do next:
  outcome: job needs verification
  comments: none
Pick an action
  c => add a comment
  p => set outcome to pass
  f => set outcome to fail
  s => set outcome to skip
  r => re-run this job
    => set suggested outcome [job passed]
[cpfsr]: 
--------------------------------------------------------------------------------
Outcome: job passed

Overall, the PR could fix the problem! Thank you @Hook25

[fernando79513]

LGTM +1!