Gitea Actions does not implement fail-fast/max-parallel for matrix jobs,
so a failing runner does not stop the others. Added molecule_ci_guard.py
which polls the Gitea API in a background thread. If any other molecule
runner reports failure, the current runner kills its molecule subprocess
and exits early.
CI returns to a 3-runner matrix; each runner executes its assigned pairs
in parallel via run_molecule_parallel.py, guarded by molecule_ci_guard.py.
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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
