syz-cluster: initial code #14968

Job	Run time
aux	4m 36s
build	13m 28s
arch (presubmit_arch_linux)	10m 56s
dashboard	3m 34s
arch (presubmit_arch_freebsd)	6m 37s
gvisor	4m 19s
arch (presubmit_arch_netbsd)	4m 25s
arch (presubmit_arch_openbsd)	4m 19s
arch (presubmit_arch_darwin)	4m 25s
old	6m 39s
arch (presubmit_arch_windows)	3m 22s
arch (presubmit_arch_executor)	3m 16s
race	8m 30s
race_dashboard	5m 7s
	1h 23m 33s

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