syz-cluster: run more workflows in parallel #17557

Job	Run time
aux	3m 56s
build	3m 19s
dashboard	2m 27s
race_dashboard	3m 39s
arch (presubmit_arch_freebsd)	6m 24s
arch (presubmit_arch_netbsd)	3m 45s
arch (presubmit_arch_linux)	10m 38s
arch (presubmit_arch_openbsd)	3m 52s
arch (presubmit_arch_darwin)	3m 34s
old	7m 9s
arch (presubmit_arch_executor)	3m 12s
race	8m 42s
gvisor	3m 47s
arch (presubmit_arch_windows)	3m 29s
	1h 7m 53s

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