Don't test pipe modes nobody uses.

SkDeferredCanvas uses a simple pipe: no cross-process, no shared-address, etc.
(see src/utils/SkDeferredCanvas.cpp:306).

We could just remove these modes from the bot configs, but I'd like to take the
opportunity to simplify the DM code too.  I'll happily volunteer to put things
back should we decide we want to test these modes.

BUG=skia:

Review URL: https://codereview.chromium.org/861303003
3 files changed