[yang]: update Yang models for cloudtype and region (#9425)

Why I did it
#9122
DEVICE_METADATA does not have cloudtype and region.

How I did it
Add cloudtype and region to DEVICE_METADATA.

How to verify it
Follow the steps in #9122.
Build sonic-yang-model.

Signed-off-by: Gang Lv ganglv@microsoft.com

src/sonic-yang-models/tests/files/sample_config_db.json

@@ -280,7 +280,9 @@
                 "hostname": "asw.dc",
                 "bgp_asn": "64850",
                 "hwsku": "Stone",
-                "buffer_model": "dynamic"
+                "buffer_model": "dynamic",
+                "cloudtype": "Public",
+                "region": "usfoo"
             }
         },
         "VLAN": {

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

@@ -54,6 +54,9 @@
     },
     "DEVICE_METADATA_FRR_MGMT_FWK_CONFIG": {
         "desc": "Verifying FRR MGMT framework configuration."
+    },
+    "DEVICE_METADATA_CORRECT_CLOUDTYPE_REGION_CONFIG": {
+        "desc": "Verifying cloudtype and region configuration."
     }
 
 }

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

@@ -139,5 +139,15 @@
                 }
             }
         }
+    },
+    "DEVICE_METADATA_CORRECT_CLOUDTYPE_REGION_CONFIG": {
+        "sonic-device_metadata:sonic-device_metadata": {
+            "sonic-device_metadata:DEVICE_METADATA": {
+                "sonic-device_metadata:localhost": {
+                    "cloudtype": "Public",
+                    "region": "usfoo"
+                }
+            }
+        }
     }
 }

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

@@ -120,6 +120,14 @@ module sonic-device_metadata {
                     }
                     default enable;
                 }
+
+                leaf cloudtype {
+                    type string;
+                }
+
+                leaf region {
+                    type string;
+                }
             }
             /* end of container localhost */
         }