Make sure same displays are shown in the CI environment

doc/.gitignore

@@ -1,2 +1,3 @@
 usage.*
 output.*
+!output.list

doc/output.list

@@ -0,0 +1,60 @@
+screen 0: 1920x1080 (min 320x200, max 16384x16384) (531mm x 299mm) (window 1946)
+output HDMI-1
+output eDP-1: (309mm x 173mm) (fpr 0x57a9d7d6)
+   1920x1080 59.98+ 59.97d 59.96 59.93
+   1680x1050 59.95 59.88
+   1400x1050 59.98
+   1600x900 59.99d 59.94d 59.95 59.82
+   1280x1024 60.02
+   1400x900 59.96 59.88
+   1280x960 60.00
+   1440x810 60.00d 59.97d
+   1368x768 59.88 59.85
+   1280x800 59.99d 59.97d 59.81 59.91
+   1280x720 60.00d 59.99d 59.86 59.74
+   1024x768 60.04d 60.00
+   960x720 60.00d
+   928x696 60.05d
+   896x672 60.01d
+   1024x576 59.95d 59.96d 59.90 59.82
+   960x600 59.93d 60.00d
+   960x540 59.96d 59.99d 59.63 59.82
+   800x600 60.00d 60.32 56.25
+   840x525 60.01d 59.88d
+   864x486 59.92 59.57
+   700x525 59.98d
+   800x450 59.95d 59.82d
+   640x512 60.02d
+   700x450 59.96d 59.88d
+   640x480 60.00d 59.94
+   720x405 59.51 58.99
+   684x384 59.88d 59.85d
+   640x400 59.88d 59.98d
+   640x360 59.86d 59.83d 59.84 59.32
+   512x384 60.00d
+   512x288 60.00d 59.92d
+   480x270 59.63d 59.82d
+   400x300 60.32d 56.34d
+   432x243 59.92d 59.57d
+   320x240 60.05d
+   360x202 59.51d 59.13d
+   320x180 59.84d 59.32d
+output DP-2
+output HDMI-2: primary 1920x1080+0+0 (531mm x 299mm) (fpr 0x43b791a2)
+   1920x1080 60.00+* 50.00 59.94 60.00i 50.00i 59.94i
+   1680x1050 59.88
+   1600x900 60.00
+   1280x1024 75.02 60.02
+   1280x800 59.91
+   1152x864 75.00
+   1280x720 60.00 50.00 59.94
+   1024x768 75.03 60.00
+   832x624 74.55
+   800x600 75.00 60.32
+   720x576 50.00 50.00i
+   720x480 60.00 59.94 60.00i 59.94i
+   640x480 75.00 60.00 59.94
+   720x400 70.08
+output DP-1
+monitor HDMI-2: active primary automatic 1920x1080+0+0 (531mm x 299mm)
+  output HDMI-2