message: turn back on draining in test
diff: <engine type="BP4">
  <parameter key="BurstBufferPath" value="bb"/>
  - <parameter key="BurstBufferDrain" value="Off"/>
  + <parameter key="BurstBufferDrain" value="On"/>
  <parameter key="BurstBufferVerbose" value="2"/>
  <parameter key="SubStreams" value="1"/>
  