unittests: use 0.1.2.3 for device IPs

We use 1.1.1.1 as a "dummy" IP in unittests when we need a host that
doesn't exist.  However, it is a real valid IP, so if our tests aren't
mocked correctly, we might attempt to ping/ssh/etc... the remote.  Use
0.1.2.3 instead as it's a valid IP and has been reserved by the spec
as a non-routable or connectable address.  It will fail immediately.

BUG=chromium:997354
TEST=`./run_tests` passes

Change-Id: Ied2c902d9d41093e1dd5bdebde54816d054b20ec
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1932722
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/cli/flash_unittest.py b/cli/flash_unittest.py
index 23cc77d..3e398db 100644
--- a/cli/flash_unittest.py
+++ b/cli/flash_unittest.py
@@ -69,7 +69,7 @@
 
   IMAGE = '/path/to/image'
   DEVICE = commandline.Device(scheme=commandline.DEVICE_SCHEME_SSH,
-                              hostname='1.1.1.1')
+                              hostname=remote_access.TEST_IP)
 
   def setUp(self):
     """Patches objects."""