autotest: drop port # from retrying_afe destination_server stats

Local calls are having destination logged with with hostname and port
number. This has the potentially to cause a too-many-streams problem.

BUG=chromium:724529
TEST=None

Change-Id: I65203da04c99c5bc8ac9f1dc000a243db67cab78
Reviewed-on: https://chromium-review.googlesource.com/515046
Commit-Ready: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Xixuan Wu <xixuan@chromium.org>
diff --git a/server/cros/dynamic_suite/frontend_wrappers.py b/server/cros/dynamic_suite/frontend_wrappers.py
index 8e85ff3..39f3501 100644
--- a/server/cros/dynamic_suite/frontend_wrappers.py
+++ b/server/cros/dynamic_suite/frontend_wrappers.py
@@ -128,7 +128,7 @@
                 c = metrics.Counter(
                         'chromeos/autotest/retrying_afe/retry_timeout')
                 # Reserve field job_details for future use.
-                f = {'destination_server': self.server,
+                f = {'destination_server': self.server.split(':')[0],
                      'call': call,
                      'job_details': ''}
                 c.increment(fields=f)