Integrate gitlab-ci/depend-pipeline-execution-on-branch-protection-state and 2 more

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@939ade2b

Depend intgration pipeline execution on branch protection state

Previously we had the master branch hard-coded in a variable in order to
determine whether to run the integration pipeline (on non-master branch)
or the merge pipeline (on master branch). This variable had to be
adapted everytime we copy a branch, which can potentially be forgotten
and lead to problems.

Remove the hard-coded branch and use the branch protection state for
this decision instead in order to make this more flexible.

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@dbc49ad0

Simplify yamllint job rules

The rules for the yamllint jobs have been defined in the .yamllint class
before. They were overridden in the manifest pipeline's yamllint job,
though, which has its own rules, so we don't need them to be inherited
in this case. And in the manifest integration pipeline the rules can be
much easier, so define them there instead of at the class-level.

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@cd8de4ff

.gitlab-ci: add analyze stage for limiting YAML script blocks