syz-cluster: display the number of findings per series and more #16163

Job	Run time
dashboard	2m 37s
build	3m 12s
aux	4m 11s
arch (presubmit_arch_linux)	10m 24s
arch (presubmit_arch_netbsd)	3m 56s
arch (presubmit_arch_windows)	3m 38s
race	7m 20s
arch (presubmit_arch_freebsd)	6m 14s
race_dashboard	3m 8s
gvisor	3m 31s
arch (presubmit_arch_darwin)	3m 52s
arch (presubmit_arch_openbsd)	3m 52s
old	6m 59s
arch (presubmit_arch_executor)	3m 30s
	1h 6m 24s

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