dashboard/app: integrate tail reports #17781

Job	Run time
race_dashboard	2m 41s
aux	4m 26s
build	4m 7s
dashboard	2m 10s
old	8m 24s
gvisor	3m 50s
race	9m 37s
arch (presubmit_arch_openbsd)	3m 46s
arch (presubmit_arch_linux)	10m 11s
arch (presubmit_arch_netbsd)	3m 43s
arch (presubmit_arch_darwin)	3m 39s
arch (presubmit_arch_windows)	3m 30s
arch (presubmit_arch_executor)	3m 12s
arch (presubmit_arch_freebsd)	6m 13s
	1h 9m 29s

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