Integrate gitlab-ci/remove-needless-variables and 3 more

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@5e36715e

Remove needless variables from build.env

There were three variables set in build.env of which the values are
already known in the environment for all jobs, because they are passed
from the parent pipeline. Use the original variables instead of defining
new ones.

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@84aa6afb

Fix LAVA job name

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@8160c7d5

Sourcery: enable "low-code-quality" check globally

Disable it locally instead, so that
 1. new code additions are always checked, and
 2. we can refactor one function at a time to make the check pass.

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@ef60c378

Sourcery: keep "for-append-to-extend" check disabled

This is another check that suggests changes an average developer without
profound Python experience would find hard to understand. Disable it.

See for reference:
https://docs.sourcery.ai/Reference/Python/Default-Rules/for-append-to-extend/