Integrate gitlab-ci/add-build-version-job and 2 more

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@53b904e3

Add yocto version job

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@1860ca8e

Remove LOG_PREFIX variable

This was used in times when the same code was executed from different
places. We don't do that anymore, so the variable is obsolete.

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@3d2dbe4d

Documentation: update job generation chapter