VMs with security groups allowing all egress traffic cannot access the Internet in 4.23.0.0

### problem

# Description

In CloudStack 4.23.0.0, a VM cannot access the Internet when its security group has egress rules configured, even when the egress rules allow all outbound traffic (0.0.0.0/0).

The same configuration works as expected in older CloudStack versions.

The issue occurs when the security group has egress rules but no ingress rules.

# Expected behavior

The VM should be able to initiate outbound connections to the Internet when the security group has an egress rule allowing all traffic.

According to the CloudStack documentation:
```
If there is no Egress rule in a Security Group, all the outgoing traffic will be allowed.
If there are Egress rules in a Security Group, only the outgoing traffic which match a Egress rule will be allowed.
Only the incoming traffic which match a Ingress rule will be allowed.
```

# Actual behavior

With CloudStack 4.23.0.0:

- The VM has a security group assigned.
- The security group has one egress rule allowing ALL outbound traffic.
- There are no ingress rules.
- The VM cannot access the Internet.

### versions

The versions of ACS, hypervisors, storage, network etc..

### The steps to reproduce the bug

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### What to do about it?

_No response_

No files, tests, or entry points are identified. First reproduce the 4.23.0.0 case with an egress-only security group allowing 0.0.0.0/0, then compare it with an older working version and trace the security-group egress path. Done means the VM can initiate Internet connections with no ingress rules and the relevant regression is covered by a test.

Written by the indexing model from the issue text.