In the current implementation, the Compute Engine has an hard coded number of Threads available to process background tasks of 1.
Users should be able to define property sonar.ce.workerCount in sonar.properties.
Value of this property is an integer and strictly greater than 0. If undefined, default value will be 1. If value is incorrect, SonarQube should fail at startup.
Value of this property should be visible in system info (and optionally in CE's MBean)