[tools/perf] Disable load:tools:drive system health story

Story shows a high failure rate on many different perf bots.

TBR=nednguyen@google.com
BUG=715936

Review-Url: https://codereview.chromium.org/2848573002
Cr-Commit-Position: refs/heads/master@{#467640}

tools/perf/page_sets/system_health/loading_stories.py

@@ -356,6 +356,7 @@ class LoadWeatherStory(_LoadingStory):
   TAGS = [story_tags.JAVASCRIPT_HEAVY]
 
 
+@decorators.Disabled('all')  # crbug.com/715936
 class LoadDriveStory(_LoadingStory):
   NAME = 'load:tools:drive'
   URL = 'https://drive.google.com/drive/my-drive'