NMstate removes egressip in OpenShift cluster with SDN plugin

This is a clone of issue OCPBUGS-5926. The following is the description of the original issue:
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This is a clone of issue OCPBUGS-4486. The following is the description of the original issue:
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This is a clone of issue OCPBUGS-95. The following is the description of the original issue:
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In an OpenShift cluster with OpenShiftSDN network plugin with egressIP and NMstate operator configured, there are some conditions when the egressIP is deconfigured from the network interface.

The bug is 100% reproducible.

Steps for reproducing the issue are:

1. Install a cluster with OpenShiftSDN network plugin.

2. Configure egressip for a project.

3. Install NMstate operator.

4. Create a NodeNetworkConfigurationPolicy.

5. Identify on which node the egressIP is present.

6. Restart the nmstate-handler pod running on the identified node.

7. Verify that the egressIP is no more present.

Restarting the sdn pod related to the identified node will reconfigure the egressIP in the node.

This issue has a high impact since any changes triggered for the NMstate operator will prevent application traffic. For example, in the customer environment, the issue is triggered any time a new node is added to the cluster.

The expectation is that NMstate operator should not interfere with SDN configuration.