test health monitor:
https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/testDetails?testName=telemetry_Benchmarks.loading.desktop

Most failure on DUT with less RAM.

Error log:

(ERROR) 2018-09-09 16:40:02,520 story_runner.ProcessError:100  Unhandleable error. Benchmark run will be interrupted
Traceback (most recent call last):
  File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py", line 118, in _RunStoryAndProcessErrorIfNeeded
    state.WillRunStory(story)
  File "/usr/local/telemetry/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 75, in traced_function
    return func(*args, **kwargs)
  File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/page/shared_page_state.py", line 223, in WillRunStory
    archive_path, page.make_javascript_deterministic, self._extra_wpr_args)
  File "/usr/local/telemetry/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 75, in traced_function
    return func(*args, **kwargs)
  File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/core/network_controller.py", line 44, in StartReplay
    archive_path, make_javascript_deterministic, extra_wpr_args)
  File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/platform/network_controller_backend.py", line 150, in StartReplay
    local_ports = self._StartReplayServer()
  File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/platform/network_controller_backend.py", line 173, in _StartReplayServer
    return self._wpr_server.StartServer()
  File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/util/webpagereplay_go_server.py", line 238, in StartServer
    'Web Page Replay failed to start. Log output:\n%s' % log_output)
ReplayNotStartedError: Web Page Replay failed to start. Log output:
2018/09/09 16:37:57 Loading cert from /usr/local/telemetry/src/third_party/catapult/web_page_replay_go/wpr_cert.pem
2018/09/09 16:37:57 Loading key from /usr/local/telemetry/src/third_party/catapult/web_page_replay_go/wpr_key.pem
2018/09/09 16:37:57 Loading script from /usr/local/telemetry/src/third_party/catapult/web_page_replay_go/deterministic.js
2018/09/09 16:37:57 Loading archive file from /usr/local/telemetry/src/tools/perf/page_sets/data/loading_desktop_006.wprgo
runtime: out of memory: cannot allocate 1073741824-byte block (1075838976 in use)
fatal error: out of memory

Add loading.desktop to ON_DUT_BLACKLIST to avoid the OOM on DUT issue.