dashboard/app: enable coverage pages formatting #16159

Job	Run time
aux	4m 5s
build	1m 51s
race_dashboard	1m 38s
dashboard	1m 39s
race	6m 39s
arch (presubmit_arch_freebsd)	6m 18s
arch (presubmit_arch_linux)	8m 59s
old	6m 48s
arch (presubmit_arch_darwin)	3m 44s
arch (presubmit_arch_openbsd)	3m 40s
arch (presubmit_arch_windows)	3m 33s
arch (presubmit_arch_netbsd)	3m 47s
arch (presubmit_arch_executor)	3m 29s
gvisor	3m 32s
	59m 42s

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