dashboard: increase timeout scale for longtest builders, add more CPU
dashboard: increase timeout scale for longtest builders, add more CPU

Updates golang/go#25886

Change-Id: I5168e291ab77cbd3843bdc39e319a68dfa65aedd
Reviewed-on: https://go-review.googlesource.com/c/build/+/167638
Reviewed-by: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

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