[rdbms] az postgresql flexible-server create: Handle failed IP address check (#31834)

Author: cclark-work

src/azure-cli/azure/cli/command_modules/rdbms/flexible_server_virtual_network.py

@@ -454,7 +454,15 @@ def prepare_private_dns_zone(db_context, resource_group, server_name, private_dn
 
 def prepare_public_network(public_access, yes):
     if public_access is None:
-        ip_address = get(IP_ADDRESS_CHECKER).text
+        try:
+            # In USSec and USNat, the IP address checker is not available as the public Internet is not accessible.
+            # When the user does not provide a public IP address or does not disble public access,
+            # the `az cli postgres flexible-server create` command will fail with the error
+            # HTTPSConnectionPool(host='api.ipify.org', port443): Max retries excceeded with url
+            ip_address = get(IP_ADDRESS_CHECKER).text
+        except Exception as ex:
+            raise CLIError("Unable to detect your current IP address. Please provide a valid IP address or CIDR range for --public-access parameter or set --public-access Disabled. Error: {}".format(ex))
+
         logger.warning("Detected current client IP : %s", ip_address)
         if yes:
             return ip_address, ip_address