auth.py: Stop writing to log every time.

BUG=None
TEST=None

Change-Id: Id2f36f7fcb8e1a0e0a5035dab606b5764a34e235
Reviewed-on: https://chromium-review.googlesource.com/1556501
Commit-Ready: Dhanya Ganesh <dhanyaganesh@chromium.org>
Tested-by: Dhanya Ganesh <dhanyaganesh@chromium.org>
Reviewed-by: Dhanya Ganesh <dhanyaganesh@chromium.org>
diff --git a/lib/auth.py b/lib/auth.py
index a276950..d3e906f 100644
--- a/lib/auth.py
+++ b/lib/auth.py
@@ -73,7 +73,7 @@
 
   result = cros_build_lib.RunCommand(
       cmd,
-      mute_output=False,
+      mute_output=True,
       error_code_ok=True)
 
   if result.returncode: