perf_upload: make "error while uploading" message less scary

We've had several bugs filed against us in which people think
"tko parser: Error when uploading perf data to the perf dashboard"
is the reason their tests failed. Instead let's highlight that this is
not a critical issue.

BUG=chromium:1128634
TEST=N/A

Change-Id: I61bccb827bbf69668a9090178d03ac4a6a9d1658
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2593918
Reviewed-by: Prathmesh Prabhu <pprabhu@google.com>
Commit-Queue: Sean Abraham <seanabraham@chromium.org>
Tested-by: Sean Abraham <seanabraham@chromium.org>
diff --git a/tko/perf_upload/perf_uploader.py b/tko/perf_upload/perf_uploader.py
index d94af55..7834da3 100644
--- a/tko/perf_upload/perf_uploader.py
+++ b/tko/perf_upload/perf_uploader.py
@@ -394,7 +394,7 @@
                                             presentation_info, jobname)
         _send_to_dashboard(formatted_data)
     except PerfUploadingError as e:
-        tko_utils.dprint('Error when uploading perf data to the perf '
+        tko_utils.dprint('Warning: unable to upload perf data to the perf '
                          'dashboard for test %s: %s' % (test_name, e))
     else:
         tko_utils.dprint('Successfully uploaded perf data to the perf '