docs: explain that a GraalVM needs build-essential and zlib1g-dev only for native-image, which GraalVM CE 8 to 19 do not include; ci: stop a newer commit on main from cancelling the e2e run of an older one

docs: explain that a GraalVM needs build-essential and zlib1g-dev only for native-image, which GraalVM CE 8 to 19 do not include; ci: stop a newer commit on main from cancelling the e2e run of an older one #88