Addition of new datacenter codes to databox rest-api-specs preview file (Azure#17279)

* Added new datacenter codes to databox rest-api-specs preview repo

* Removed YQB20 from the new additions

Author: urguru

specification/databox/resource-manager/Microsoft.DataBox/preview/2021-08-01-preview/databox.json

@@ -3330,7 +3330,10 @@
             "PUS20",
             "AdHoc",
             "CH1",
-            "DSM05"
+            "DSM05",
+            "BN7",
+            "SN6",
+            "PAR22"
           ],
           "type": "string",
           "readOnly": true,
@@ -3487,6 +3490,15 @@
               },
               {
                 "value": "DSM05"
+              },
+              {
+                "value": "BN7"
+              },
+              {
+                "value": "SN6"
+              },
+              {
+                "value": "PAR22"
               }
             ]
           }