bench,gc_latency: use -short to limit gc_latency output

There's only a few measurements we really care about, and
they also seem to actually be less noisy.  Even if they
weren't, this reduces the number of measurements reported
by about 80%.

Change-Id: Id1a93c97d74f27eb2b61f6a95bf2452578d4e8c4
LUCI-TryBot-Result: Go LUCI <>
Reviewed-by: Michael Knyszek <>
3 files changed