[CI/CD] Use original PR name in prdoc check for the backport PR's to the stable branches#8329

EgorPopelyaev merged 10 commits intoparitytech:masterparitytech/polkadot-sdk:masterfrom

EgorPopelyaev:ep-use-original-pr-name-in-prdoc-checkEgorPopelyaev/polkadot-sdk:ep-use-original-pr-name-in-prdoc-checkCopy head branch name to clipboard