Run release-environments pipeline from the same branch

What does this MR do and why?

Run release-environments pipeline from the same branch

Previously, the release-environments pipeline is always triggered from master pipeline so that we don't need to backport pipeline changes to stable branches whenever a change is made. However, this strategy doesn't fit anymore:

• The pipeline is quite stable now, so we don't make changes often.
• The mismatch between the commit ref using for the upstream and downstream pipelines sometimes leads to unexpected behaviors (e.g. a QA image build in master may not work with the QA setup in the stable branches)

References

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• gitlab-org/release/tasks#15464 (closed)

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