syz-cluster: initial code #15156

Job	Run time
aux	4m 51s
build	13m 29s
dashboard	3m 42s
arch (presubmit_arch_linux)	11m 7s
arch (presubmit_arch_freebsd)	6m 29s
gvisor	4m 14s
old	6m 38s
arch (presubmit_arch_netbsd)	4m 34s
race	7m 47s
race_dashboard	3m 20s
arch (presubmit_arch_openbsd)	4m 21s
arch (presubmit_arch_darwin)	4m 18s
arch (presubmit_arch_windows)	3m 27s
arch (presubmit_arch_executor)	3m 17s
	1h 21m 34s

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