Avoid setting framework/system counters for tasks running in threads

Counters like FileSystemCounters, GC_TIME, CPU_TIME etc - are computed incorrectly in case of LocalMode, Uber, TestService and others where tasks may execute in threads. (The values end up being a combination of what's running in the process - which could be other tasks or the AM).
It's better not to set them for now, instead of reporting incorrect values.