xen: set Network.managed to true before creating the network

This should fix
```
2025-04-07 12:08:20,472 WARN  [c.c.h.x.r.w.x.CitrixStartCommandWrapper] (DirectAgent-36:[ctx-a59ea070]) (logid:97c16f84) Catch Exception: class com.xensource.xenapi.Types$NetworkUnmanaged due to The network is not managed by xapi. The network is not managed by xapi.
        at com.xensource.xenapi.Types.checkResponse(Types.java:2514)
        at com.xensource.xenapi.Connection.dispatch(Connection.java:266)
        at com.cloud.hypervisor.xenserver.resource.XenServerConnectionPool$XenServerConnection.dispatch(XenServerConnectionPool.java:458)
        at com.xensource.xenapi.VLAN.create(VLAN.java:363)
        at com.cloud.hypervisor.xenserver.resource.CitrixResourceBase.enableVlanNetwork(CitrixResourceBase.java:1736)
        at com.cloud.hypervisor.xenserver.resource.CitrixResourceBase.getNetwork(CitrixResourceBase.java:2885)
        at com.cloud.hypervisor.xenserver.resource.CitrixResourceBase.createVif(CitrixResourceBase.java:1280)
        at com.cloud.hypervisor.xenserver.resource.wrapper.xenbase.CitrixStartCommandWrapper.execute(CitrixStartCommandWrapper.java:106)
        at com.cloud.hypervisor.xenserver.resource.wrapper.xenbase.CitrixStartCommandWrapper.execute(CitrixStartCommandWrapper.java:56)
        at com.cloud.hypervisor.xenserver.resource.wrapper.xenbase.CitrixRequestWrapper.execute(CitrixRequestWrapper.java:122)
        at com.cloud.hypervisor.xenserver.resource.CitrixResourceBase.executeRequest(CitrixResourceBase.java:1791)
```

refer to CA-387821: SDK Tests/JavaSDK failed. Set Network.managed to true before creating the network.
xenserver/xenserver-samples@1684db5

Author: weizhouapache

plugins/hypervisors/xenserver/src/main/java/com/cloud/hypervisor/xenserver/resource/CitrixResourceBase.java

@@ -1713,6 +1713,7 @@ protected Network enableVlanNetwork(final Connection conn, final long tag, final
             nwr.nameLabel = newName;
             nwr.tags = new HashSet<String>();
             nwr.tags.add(generateTimeStamp());
+            nwr.managed = true;
             vlanNetwork = Network.create(conn, nwr);
             vlanNic = getNetworkByName(conn, newName);
             if (vlanNic == null) { // Still vlanNic is null means we could not
@@ -2018,6 +2019,7 @@ public synchronized Network findOrCreateTunnelNetwork(final Connection conn, fin
                 // started
                 otherConfig.put("assume_network_is_shared", "true");
                 rec.otherConfig = otherConfig;
+                rec.managed = true;
                 nw = Network.create(conn, rec);
                 logger.debug("### XenServer network for tunnels created:" + nwName);
             } else {
@@ -4882,6 +4884,7 @@ public void setupLinkLocalNetwork(final Connection conn) {
                 configs.put("netmask", NetUtils.getLinkLocalNetMask());
                 configs.put("vswitch-disable-in-band", "true");
                 rec.otherConfig = configs;
+                rec.managed = true;
                 linkLocal = Network.create(conn, rec);
             } else {
                 linkLocal = networks.iterator().next();
@@ -5073,6 +5076,7 @@ public synchronized Network setupvSwitchNetwork(final Connection conn) {
                 if (networks.size() == 0) {
                     rec.nameDescription = "vswitch network for " + nwName;
                     rec.nameLabel = nwName;
+                    rec.managed = true;
                     vswitchNw = Network.create(conn, rec);
                 } else {
                     vswitchNw = networks.iterator().next();