minor ci.syzbot.org improvements #18442

Job	Run time
gvisor	4m 3s
race_dashboard	2m 52s
aux	4m 44s
old	7m 8s
dashboard	1m 49s
arch (presubmit_arch_openbsd)	3m 41s
arch (presubmit_arch_freebsd)	6m 15s
arch (presubmit_arch_darwin)	3m 43s
race	8m 46s
build	1m 42s
arch (presubmit_arch_netbsd)	3m 41s
arch (presubmit_arch_windows)	3m 29s
arch (presubmit_arch_executor)	2m 40s
arch (presubmit_arch_linux)	10m 41s
	1h 5m 14s

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