Update OOM query to 1.9.7 message format

Auditors: csilvers

Test Plan:
Fingers crossed for the code. I ran this for an hour's worth of logs via
the BQ web UI and saw that it did extract the value:

  SELECT app_logs.message,
         REGEXP_EXTRACT(app_logs.message, r'servicing (\d+) requests') as val
  FROM [logs_hourly.requestlogs_20140721_00]
  WHERE app_logs.message CONTAINS 'Exceeded soft private memory limit'
  ORDER by val
  DESC LIMIT 500;