dashboard/app: fix menu items height #19038

Job	Run time
old	7m 10s
dashboard	2m 13s
build	3m 40s
race_dashboard	2m 54s
gvisor	4m 20s
arch (presubmit_arch_openbsd)	3m 45s
arch (presubmit_arch_windows)	3m 37s
arch (presubmit_arch_netbsd)	3m 59s
aux	4m 6s
arch (presubmit_arch_freebsd)	6m 23s
arch (presubmit_arch_darwin)	3m 44s
arch (presubmit_arch_linux)	10m 59s
arch (presubmit_arch_executor)	3m 23s
race	7m 16s
	1h 7m 29s

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