Specify the ADB keys to use for ADB

In the golo, specifically, the adb keys used by swarming
are different than those used in the docker instance, unless
configured otherwise.

This means swarming can think a device is ready (authorized)
but the adb we called was not (authorized)

Bug: 843284
No-Tree-Checks: true
No-Try: true
No-Presubmit: true
Change-Id: I7e77556114207657ec0ef7a22fc90bac25ec1374
Reviewed-on: https://skia-review.googlesource.com/129170
Reviewed-by: Eric Boren <borenet@google.com>
Reviewed-by: Heather Miller <hcm@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
52 files changed