Add missing variant & k3s version to uki pipeline

[mauromorales]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #2983

[Itxaka]

do we? Or do we want to push using sysextensions for this?

[mauromorales]

@Itxaka we can push for sysext for this, but meanwhile, both core and standard are broken. I don't mind removing the standard one if we want to do this via sysext, but I'm not sure how that would work because we'd need to have those signed

[Itxaka]

@Itxaka we can push for sysext for this, but meanwhile, both core and standard are broken. I don't mind removing the standard one if we want to do this via sysext, but I'm not sure how that would work because we'd need to have those signed

I don't get how this is broken and how adding k3s makes it work?

Also sysext are also signed, same as the images and everything UKI, so not sure what that has to do with anything? We provide base artifacts, unsigned and the user needs to build based on those and sign those to work. I don't get how providing k3s in the base image would improve that ?

Also, doesn't this make the image bigger so it potentially makes it difficult-er to boot on stupid EFI firmwares that have EFI size restrictions?

[mauromorales]

Ok merging this and we can have a look at the test in a different PR plus have a ticket for sysext