SA B200 gNB CI test: use host-mode

ci-scripts/yaml_files/sa_b200_gnb/docker-compose.yml

@@ -11,9 +11,11 @@ services:
         volumes:
             - ../../conf_files/gnb.sa.band78.51prb.usrpb200.conf:/opt/oai-gnb/etc/gnb.conf
             - /dev:/dev
-        networks:
-            public_net:
-                ipv4_address: 192.168.68.194
+        # for performance reasons, we use host mode: in bridge mode, we have
+        # unacceptable DL TCP performance. However, the whole point of
+        # containerization is to not be in host mode, so update this to macvlan
+        # later.
+        network_mode: "host"
         #entrypoint: /bin/bash -c "sleep infinity"
         healthcheck:
             # pgrep does NOT work
@@ -21,12 +23,3 @@ services:
             interval: 10s
             timeout: 5s
             retries: 5
-
-networks:
-    public_net:
-        name: sa-b200-gnb-net
-        ipam:
-            config:
-                - subnet: 192.168.68.192/26
-        driver_opts:
-            com.docker.network.bridge.name: "sa-gnb-net"