Add automatic retries to nightly testing.

Used new "retries" crosperf functionality in our nightly testing.

BUG=None
TEST=None (already tested in crosperf side)

Change-Id: I42b9d04ef690593485df825b2a3aa41b9e2f6cc3
Reviewed-on: https://chrome-internal-review.googlesource.com/219310
Reviewed-by: Han Shen <shenhan@google.com>
Commit-Queue: Luis Lozano <llozano@chromium.org>
Tested-by: Luis Lozano <llozano@chromium.org>
diff --git a/buildbot_test_toolchains.py b/buildbot_test_toolchains.py
index 7099038..9b8a79f 100755
--- a/buildbot_test_toolchains.py
+++ b/buildbot_test_toolchains.py
@@ -94,6 +94,7 @@
     experiment_header = """
     board: %s
     remote: %s
+    retries: 1
     """ % (self._board, self._remotes)
     experiment_tests = """
     benchmark: all_perfv2 {