Disable default route in dpu (sonic-net#21393)

Signed-off-by: Yue Gao <[email protected]>
Signed-off-by: Zhuohui Tan <[email protected]>

Author: yue-fred-gao

ansible/library/generate_golden_config_db.py

@@ -467,7 +467,6 @@ def generate_smartswitch_golden_config_db(self):
         dhcp_server_ipv4_config = {
             "DHCP_SERVER_IPV4": {
                 "bridge-midplane": {
-                    "gateway": "169.254.200.254",
                     "lease_time": "600000000",
                     "mode": "PORT",
                     "netmask": "255.255.255.0",