[yang] Add t2_group_asns in yang model (#22262)

Why I did it
Radian T2 support was added by this PR #21732
We need to deny anchor routes from RH with ASNs in same DCs, hence need a attr to store asns in same DC

Work item tracking
Microsoft ADO (number only): 31979687

How I did it
Add t2_group_asns in DEVICE_METADATA

How to verify it
UT passed

Author: yaqiangz

src/sonic-yang-models/tests/yang_model_tests/tests/device_metadata.json

@@ -197,7 +197,11 @@
     "DEVICE_METADATA_VALID_SLICE_TYPE": {
         "desc": "Verifying valid slice_type configuration."
     },
-    "DEVICE_METADATA_VALID_NEXTHOP_GROUP": {
-        "desc": "Verifying nexthop_group configuration."
-     }
+    "DEVICE_METADATA_VALID_T2_GROUP_ASNS": {
+        "desc": "Verifying valid t2_group_asns."
+     },
+     "DEVICE_METADATA_VALID_T2_GROUP_ASNS_INVALID": {
+         "desc": "Verifying invalid t2_group_asns.",
+         "eStrKey": "InvalidValue"
+      }
 }

src/sonic-yang-models/tests/yang_model_tests/tests_config/device_metadata.json

@@ -563,5 +563,23 @@
                 }
             }
         }
+    },
+    "DEVICE_METADATA_VALID_T2_GROUP_ASNS": {
+        "sonic-device_metadata:sonic-device_metadata": {
+            "sonic-device_metadata:DEVICE_METADATA": {
+                "sonic-device_metadata:localhost": {
+                    "t2_group_asns": ["65000", "65001", "65002"]
+                }
+            }
+        }
+    },
+    "DEVICE_METADATA_VALID_T2_GROUP_ASNS_INVALID": {
+        "sonic-device_metadata:sonic-device_metadata": {
+            "sonic-device_metadata:DEVICE_METADATA": {
+                "sonic-device_metadata:localhost": {
+                    "t2_group_asns": ["str"]
+                }
+            }
+        }
     }
 }

src/sonic-yang-models/yang-models/sonic-device_metadata.yang

@@ -290,6 +290,11 @@ module sonic-device_metadata {
                     default "false";
                 }
 
+                leaf-list t2_group_asns {
+                    type inet:as-number;
+                    description "ASNs inner same group";
+                }
+
             }
             /* end of container localhost */
         }