Describe the bug
When using APM agent on Kubernetes cluster, the memory reported in system.process.memory.size is incorrect.

To identify this situation whe have the suport of @tanquetav

To Reproduce
Steps to reproduce the behavior:

1. In kibana, search your service metrics:
   service.name : your-service-name and processor.event : metric
   this value is all memory of host.

Expected behavior
The correct value of the service.