[ci] Run CI on merge commit instead of head commit (#22)_10 (Pending, merge deferred)

[sahithiacn]

Motivation

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Test Plan

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Related PRs

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• Justification and breaking nature (who does it affect? validators, full nodes, tooling, operators, AOS, etc.)
• Comprehensive test results that demonstrate the fix working and not breaking existing workflows.
• Why we must have it for V1 launch.
• What workarounds and alternative we have if we do not push the PR.