dashboard/app: make bug lists collapsible #18756

Job	Run time
gvisor	4m 3s
build	4m 8s
race_dashboard	3m 51s
race	7m 15s
dashboard	2m 2s
arch (presubmit_arch_netbsd)	3m 57s
arch (presubmit_arch_darwin)	3m 51s
arch (presubmit_arch_freebsd)	6m 31s
arch (presubmit_arch_windows)	3m 36s
arch (presubmit_arch_openbsd)	3m 49s
aux	4m 1s
arch (presubmit_arch_executor)	3m 22s
arch (presubmit_arch_linux)	10m 49s
old	7m 19s
	1h 8m 34s

Provide feedback