Refactor: Remove NFStream and flow identity utilities; introduce Tshark manager

- Deleted flow_identity.py and nfstream_flow_worker.py as they are no longer needed.
- Removed nfstream_manager.py and its associated logic for managing NFStream workers.
- Added tshark_manager.py to manage tshark packet enrichment and matching.
- Updated setup_build_server.sh to include default environment variables for tshark.
- Implemented packet signature generation and enrichment logic in the new TsharkManager class.

backend/src/main.py

@@ -95,11 +95,11 @@ async def shutdown_event() -> None:
         logging.exception("Failed to stop bridge telemetry collector")
 
     try:
-        from src.utilities.nfstream_manager import nfstream_manager
+        from src.utilities.tshark_manager import tshark_manager
 
-        nfstream_manager.stop()
+        tshark_manager.stop()
     except Exception:
-        logging.exception("Failed to stop NFStream workers")
+        logging.exception("Failed to stop tshark workers")
 
     try:
         from src.utilities.packet_tracker import packet_tracker