Drop Ubuntu 18.04 "bionic"

Ubuntu 18.04 LTS (Bionic Beaver) is EOL.

Move gcc:bionic:amd64-specific CFLAGS and EXTRA_CONFIGURE to gcc:jammy:amd64.

CI pipeline with altered Ubuntu "jammy" jobs: https://gitlab.isc.org/isc-projects/bind9/-/pipelines/149812

Follow-up: isc-projects/images!275