lxc: avoid chromite constants

We want to break autotest's use of chromite.  This module uses a
single constant from chromite, so inline that value here instead.

BUG=chromium:1049711
TEST=CQ passes

Change-Id: I97a31b6d2159d8802a1eec646e1d5794c6941df8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2042360
Reviewed-by: Alex Zamorzaev <zamorzaev@chromium.org>
Reviewed-by: Jacob Kopczynski <jkop@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
diff --git a/site_utils/lxc/container.py b/site_utils/lxc/container.py
index 91994f5..dcdbd5a 100644
--- a/site_utils/lxc/container.py
+++ b/site_utils/lxc/container.py
@@ -22,7 +22,7 @@
 except ImportError:
     metrics = utils.metrics_mock
 
-from chromite.lib import constants as chromite_constants
+ISOLATESERVER = 'https://isolateserver.appspot.com'
 
 # Naming convention of test container, e.g., test_300_1422862512_2424, where:
 # 300:        The test job ID.
@@ -545,7 +545,7 @@
 
         return utils.run(_command.format(
             sha=isolate_hash, dest_dir=dest_path,
-            log_file=log_file, server=chromite_constants.ISOLATESERVER))
+            log_file=log_file, server=ISOLATESERVER))
 
 
     def install_control_file(self, control_file):