Trace infrastructure improvements for Junos OS-Junos OS Evolved hybrid systems

We have improved the trace infrastructure for hybrid systems, where the Routing Engine runs Junos OS and the Flexible PIC Concentrator (FPC) run Junos OS Evolved. The trace-writer on the Junos OS Routing Engine can now receive traces from the Junos OS Evolved FPCs and then store the traces in the /var/log/traces directory on the Routing Engine. The trace logs are stored in the /var/log/trace-logs directory. The FPCs no longer store any traces. We have disbled the existing show trace command on the Routing Engine for hybrid devices because these traces are not in human-readable format.