dashboard/app: fix menu items height #19039

Job	Run time
build	10m 0s
aux	3m 34s
dashboard	10m 0s
race_dashboard	10m 0s
race	10m 0s
arch (presubmit_arch_linux)	10m 49s
gvisor	4m 6s
arch (presubmit_arch_netbsd)	4m 3s
old	7m 24s
arch (presubmit_arch_darwin)	4m 0s
arch (presubmit_arch_windows)	3m 42s
arch (presubmit_arch_openbsd)	3m 50s
arch (presubmit_arch_freebsd)	6m 26s
arch (presubmit_arch_executor)	3m 36s
	1h 31m 30s

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