[ISPN-3836] Set TCCL of created threads

* The TCCL of each thread is set to infinispan's loader.
* Any calls to ServiceLoader.load that were using the
  TCCL now use the configured classloader instead (other
  than for the CLI and tests).
* DistExec services statically caching services loaded
  from the configured classloader and now cache them at
  instance level only.