disable unit tests in Google3

Many of them will start failing or crashing
once we set SK_DISABLE_READ_BUFFER there.

Alternatively, we could see if we can get away without
SK_DISABLE_READ_BUFFER.  It's small value compared to
the other flags.

Change-Id: I447cbd09f68afed81b4b1db8cc234abd22389d46
Reviewed-on: https://skia-review.googlesource.com/c/169762
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>

public.bzl

@@ -545,7 +545,7 @@ DM_INCLUDES = [
 ################################################################################
 
 def DM_ARGS(asan):
-    source = ["tests", "gm", "image", "lottie"]
+    source = ["gm", "image", "lottie"]
 
     # TODO(benjaminwagner): f16, pic-8888, serialize-8888, and tiles_rt-8888 fail.
     config = ["565", "8888", "pdf"]