Update BBR istio.yaml to use FULL_DUPLEX_STREAM (#629)

Author: rramkumar1

Diff for: config/charts/body-based-routing/templates/istio.yaml

@@ -25,9 +25,9 @@ spec:
           processing_mode:
             request_header_mode: "SEND"
             response_header_mode: "SKIP"
-            request_body_mode: "BUFFERED"
+            request_body_mode: "FULL_DUPLEX_STREAMED"
             response_body_mode: "NONE"
-            request_trailer_mode: "SKIP"
+            request_trailer_mode: "SEND"
             response_trailer_mode: "SKIP"
           grpc_service:
             envoy_grpc: