autotest: refactor status_history into a lib outside of site_utils

CQ-DEPEND=CL:378599

BUG=chromium:641093
TEST=Ran dut_status command, verified working.

Change-Id: I9f60e2dff24683e66af00c7ce1c8a825b239e782
Reviewed-on: https://chromium-review.googlesource.com/378435
Commit-Ready: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Richard Barnette <jrbarnette@google.com>
diff --git a/frontend/afe/rpc_interface.py b/frontend/afe/rpc_interface.py
index 87ea9f5..cf392a8 100644
--- a/frontend/afe/rpc_interface.py
+++ b/frontend/afe/rpc_interface.py
@@ -51,7 +51,7 @@
 from autotest_lib.server import utils
 from autotest_lib.server.cros import provision
 from autotest_lib.server.cros.dynamic_suite import tools
-from autotest_lib.site_utils import status_history
+from autotest_lib.server.lib import status_history
 
 
 _timer = autotest_stats.Timer('rpc_interface')