WIP: Do not push end-user envs to ghcr. #2

Job	Run time
build-container-image	1m 13s
Build dev-env (ubuntu-20.04)	2m 13s
Build dev-env (ubuntu-22.04)	2m 16s
Build dev-env (ubuntu-23.10)	2m 16s
Build dev-env (ubuntu-24.04)	2m 13s
Build dev-env (debian-bullseye)	1m 58s
Build dev-env (debian-bookworm)	2m 16s
Build dev-env (debian-trixie)	2m 16s
Build dev-env (fedora-39)	2m 16s
Build dev-env (fedora-40)	2m 15s
	21m 12s

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