Update android-skqp Docker image to accept licenses

Set DOCKER_CONFIG env var for all docker commands so that the Swarming
task uses the config created here:
https://skia.googlesource.com/buildbot/+/06aaf21b5d91a68de7c02aafc0fdee8531ba0c21/scripts/run_on_swarming_bots/install_docker.py#65

Bug: skia:8698
Change-Id: I731a99abc274caa498af8dde5142a7e6a6b6eca3
Reviewed-on: https://skia-review.googlesource.com/c/185690
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
Reviewed-by: Stephan Altmueller <stephana@google.com>
diff --git a/infra/bots/recipes/test_pathkit.py b/infra/bots/recipes/test_pathkit.py
index 2d3ba87..2093ec5 100644
--- a/infra/bots/recipes/test_pathkit.py
+++ b/infra/bots/recipes/test_pathkit.py
@@ -6,6 +6,7 @@
 
 DEPS = [
   'checkout',
+  'env',
   'infra',
   'recipe_engine/file',
   'recipe_engine/path',
@@ -122,10 +123,13 @@
       '--patchset',      api.vars.patchset,
     ])
 
-  api.run(
-    api.step,
-    'Test PathKit with Docker',
-    cmd=cmd)
+  # Override DOCKER_CONFIG set by Kitchen.
+  env = {'DOCKER_CONFIG': '/home/chrome-bot/.docker'}
+  with api.env(env):
+    api.run(
+        api.step,
+        'Test PathKit with Docker',
+        cmd=cmd)
 
 
 def GenTests(api):