[Task]: Figure out if the board variable FULL_DESKTOP= is still in use

[ColorfulRhino]

Task description

Many boards use the variable FULL_DESKTOP= in their board config. I can't seem to find a reference in the code though. This is from the readme:

build/config/boards/README.md

Lines 78 to 81 in c84703d

	- **FULL_DESKTOP** ( boolean ): defines whether to install desktop stack of applications such as office, thunderbird, etc..
	- Values:
	- yes: install desktop stack
	- no: doesn't install desktop stack

On the contrary, the HAS_VIDEO_OUTPUT variable seems more important and is actually referenced in the code. Maybe we should replace all occurrencs of FULL_DESKTOP with HAS_VIDEO_OUTPUT?

build/config/boards/README.md

Lines 66 to 69 in c84703d

	- **HAS_VIDEO_OUTPUT** ( boolean ): defines whether the system has video output such as eye candy, bootsplash, etc..
	- Values:
	- yes: Enable video-related configuration
	- no: Disable video-related configuration

[github-actions]

Jira ticket: AR-2414

[rpardini]

Hmm. I think at least one, if not both, of those variables are actually used in the JSON matrix for the build pipelines.

That might live somewhere under armbian/os and not here.

It's worth noting that every variable in the board file is exposed to the pipeline JSON if it matches a certain regex; some are further processed, eg, coerced into a JSON boolean.

I think HAS_VIDEO_OUTPUT is specifically used for the auto-inventory stuff:

    items-from-inventory:
      not-eos-with-video: yes # not-eos boards, all branches, only those without HAS_VIDEO_OUTPUT="no"