dashboard/app: allow quarter coverage analysis #16136

Job	Run time
aux	4m 7s
build	3m 17s
dashboard	2m 36s
gvisor	3m 30s
race	9m 10s
old	6m 50s
race_dashboard	3m 34s
arch (presubmit_arch_darwin)	3m 38s
arch (presubmit_arch_windows)	3m 40s
arch (presubmit_arch_netbsd)	3m 56s
arch (presubmit_arch_openbsd)	3m 41s
arch (presubmit_arch_executor)	3m 19s
arch (presubmit_arch_freebsd)	6m 7s
arch (presubmit_arch_linux)	10m 26s
	1h 7m 51s

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