minor changes to optimize the test

- Summary report is disabled during execution
- Thread creation is delayed in order to more efficiently use RAM 
- The corresponding fix is already made in Jenkins/Jmeter.bat to increase max heap memory allocation from 512m to 2048m. 

These changes should enable Jmeter to create enough users to stress the demo server. Otherwise, plan B is to use a distributed Jmeter environment to generate additional users(threads)