server: Don't specify ipv6 ranges for shared network (#10746)

* assume SLAAC takes care

* log info

* Update server/src/main/java/com/cloud/network/NetworkServiceImpl.java

---------

Co-authored-by: Wei Zhou <[email protected]>

Author: DaanHoogland

server/src/main/java/com/cloud/network/NetworkServiceImpl.java

@@ -1644,8 +1644,8 @@ public Network createGuestNetwork(CreateNetworkCmd cmd) throws InsufficientCapac
             if (ipv4 && Objects.isNull(startIP)) {
                 throw new CloudRuntimeException("IPv4 address range needs to be provided");
             }
-            if (ipv6 && Objects.isNull(startIPv6)) {
-                throw new CloudRuntimeException("IPv6 address range needs to be provided");
+            if (ipv6) {
+                s_logger.info(String.format("ip range for network '%s' is specified as %s - %s", name, startIPv6, endIPv6));
             }
         }
         Pair<Integer, Integer> interfaceMTUs = validateMtuConfig(publicMtu, privateMtu, zone.getId());