[infra] Enable QuadroP400 bots on rack:2

I tried to determine the differences between rack:1 and rack:2 using
trybots, but didn't have much luck. Hopefully whatever issue that was
causing differences has gone away, but if not, hopefully it will be
easier to identify the differences using Perf.

Change-Id: If9b16e8e247737cfc61bf00629eb68b8751bbf3a
Reviewed-on: https://skia-review.googlesource.com/156500
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
2 files changed