Integrate gitlab-ci/fix-reuse-of-outdated-integration-branch

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Commit: seco-ne/yocto/infrastructure/gitlab-ci@bcb6076b

CI: Add check if integration branch is on top of target branch before reusing it

The integration branch was reused even if there where new commits on the
target branch, which could lead into reverting some changes.
This adds a check, if the existing integration branch is directly based
on the target branch and deletes it if not.