Add 'retries' to crosperf for nightly non-buildbot tests.

BUG=None
TEST=None

Change-Id: Id991ed0d5e23d363940d65aeb49f4e4fbbd2051e
Reviewed-on: https://chrome-internal-review.googlesource.com/221000
Reviewed-by: Yunlian Jiang <yunlian@google.com>
Commit-Queue: Caroline Tice <cmtice@google.com>
Tested-by: Caroline Tice <cmtice@google.com>
diff --git a/test_toolchains.py b/test_toolchains.py
index 0d333d7..4717089 100755
--- a/test_toolchains.py
+++ b/test_toolchains.py
@@ -194,6 +194,7 @@
     experiment_header = """
     board: %s
     remote: %s
+    retries: 1
     """ % (self._board, self._remotes)
     experiment_tests = """
     benchmark: all_toolchain_perf {