fix: removed vnet dependancy from template

Author: srdan-bozovic-msft

samples/manage/azure-sql-db-managed-instance/attach-jumpbox/azuredeploy.json

@@ -121,7 +121,6 @@
             "apiVersion": "2017-10-01",
             "location": "[parameters('location')]",
             "dependsOn": [
-                "[concat('Microsoft.Network/virtualNetworks/', parameters('virtualNetworkName'))]",
                 "[concat('Microsoft.Network/publicIpAddresses/', variables('publicIPAddressName'))]",
                 "[concat('Microsoft.Network/networkSecurityGroups/', variables('networkSecurityGroupName'))]"
             ],