move cleanup into scheduled workflow #146

Job	Run time
build-docker-normal / build-docker-image (arm/v7)	26m 20s
build-docker-normal / build-docker-image (riscv64)	26m 6s
build-docker-normal / build-docker-image (amd64)	3m 3s
build-docker-normal / build-docker-image (arm64)	23m 59s
build-docker-normal / build-docker-image (ppc64le)	26m 34s
build-docker-normal / build-docker-image (s390x)	28m 10s
build-docker-normal / merge	30s
build-docker-minimal / build-docker-image (arm64)	33s
build-docker-minimal / build-docker-image (ppc64le)	33s
build-docker-minimal / build-docker-image (s390x)	33s
build-docker-minimal / build-docker-image (amd64)	52s
build-docker-minimal / build-docker-image (arm/v7)	30s
build-docker-minimal / build-docker-image (riscv64)	26s
build-docker-minimal / merge	15s
	2h 18m 24s

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