backport: bitcoin#27460, #27585, #28168, #28200, #28218, #28284, #28289, #28369, #28637 - #8071

On December 2, 2026, GitHub will restrict `pull_request_target` on public repositories by default. To continue allowing the event trigger, configure an Actions policy. Learn more: https://gh.io/securely-using-pull_request_target#default-policy-for-pull_request_target