NPE when destroying a vpc network which is deployed with firewall service enabled in vpc offering.

### problem

NPE when destroying a vpc network which is deployed with firewall service enabled in vpc offering.

### versions

ACS 4.23

### The steps to reproduce the bug

Steps to reproduce the issue

1. Create a vpc offering with firewall service enabled

2. Deploy a tier in the vpc network

3. Deploy a vm in the vpc tier

4. Apply firewall rules for a public ip address

4. Destroy/expunge a vm

5. Destroy the tier

6. Destroy the vpc network

Exception message

Screenshot

Logs

```
2026-09-07 07:14:11,542 DEBUG [c.c.n.IpAddressManagerImpl] (API-Job-Executor-23:[ctx-ee60323d, job-1148, ctx-02cd9ce1]) (logid:98e01084) Releasing ip IPAddress {"address":"192.168.55.84","dataCenterId":1,"id":4,"uuid":"c1fd45b4-d409-4324-8a99-d6fc5e41c59e"}; sourceNat = false
2026-09-07 07:14:11,570 ERROR [c.c.a.ApiAsyncJobDispatcher] (API-Job-Executor-23:[ctx-ee60323d, job-1148]) (logid:98e01084) Unexpected exception while executing org.apache.cloudstack.api.command.user.vpc.DeleteVPCCmd java.lang.NullPointerException: Cannot invoke "com.cloud.network.Network.getId()" because "network" is null
at com.cloud.network.IpAddressManagerImpl.applyIpAssociations(IpAddressManagerImpl.java:1283)
at com.cloud.network.IpAddressManagerImpl.disassociatePublicIpAddress(IpAddressManagerImpl.java:828)
at com.cloud.network.vpc.VpcManagerImpl.cleanupVpcResources(VpcManagerImpl.java:2705)
at com.cloud.network.vpc.VpcManagerImpl.destroyVpc(VpcManagerImpl.java:1942)
at com.cloud.network.vpc.VpcManagerImpl.deleteVpc(VpcManagerImpl.java:1901)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:569)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344)

```

### What to do about it?

VPC network should be destroyed without any exception