dashboard: skip some slow/broken tests on arm5 builder
dashboard: skip some slow/broken tests on arm5 builder

Updates golang/go#24754

Change-Id: Ie5e94a8fd0b76e6394249a734d8fc1a61650dbad
Reviewed-on: https://go-review.googlesource.com/106118
Reviewed-by: Daniel Martí <29bf28b42a938ace12a5819da4ed4ba03d82f315@mvdan.cc>

golang/build,golang/build,golang/build,golang/build