(rm-children|2/?) remove most code related to pub children #2411

Job	Run time
build-all / Emit container tag sha	5s
ci / ci	4m 16s
build-all / build-base / Build	2m 51s
build-all / build-jobs / Build	1m 41s
build-all / build-core / Build	3m 53s
deploy-preview	22s
e2e / Integration tests	10m 24s
	23m 32s

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