Remove techcrunch.com from the list of story to be run in power.top_25

BUG=498229, 489214

TBR=andresantoso@chromium.org, sullivan@chromium.org
CQ_EXTRA_TRYBOTS=tryserver.chromium.perf:mac_perf_bisect;tryserver.chromium.perf:android_nexus5_perf_bisect

Review URL: https://codereview.chromium.org/1177623003

Cr-Commit-Position: refs/heads/master@{#333725}

tools/perf/benchmarks/power.py

@@ -74,7 +74,7 @@ class PowerTop25(perf_benchmark.PerfBenchmark):
   def Name(cls):
     return 'power.top_25'
 
-  def CreateUserStorySet(self, _):
+  def CreateStorySet(self, _):
     # Exclude techcrunch.com. It is not suitable for this benchmark because it
     # does not consistently become quiescent within 60 seconds.
     user_stories = self.page_set()