gitlab CI: Update to latest CI templates & Debian stable release
Current template fails to rebuild the CI container with the current Debian stable release (a new release since the last update)
Also stop requiring Signed-off-by in commits
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The migration is almost done, at least the rest should happen in the background. There are still a few technical difference between the old cluster and the new ones, and they are summarized in this issue. Please pay attention to the TL:DR at the end of the comment.
Current template fails to rebuild the CI container with the current Debian stable release (a new release since the last update)
Also stop requiring Signed-off-by in commits