Proxy seldomly not informed about lost LB after node reboot

[zolug]

Describe the bug
It has been seen that seldomly some proxies are not informed about the disappearance of an LB that was hosted by a rebooted node.
In the most recent case the rebooted node also hosted an NSM k8s-registry (3 replicas), a spire server (3 replicas), Meridio IPAM and NSP.

It causes the old NSM interfaces to the unavailable LB POD to remain in the routing config thus causing traffic disturbance.

To Reproduce
Steps to reproduce the behavior:
???

1. Setup a cluster with 7-8 proies and 2 LBs and 3 NSM k8s registries.
2. Reboot a node hosting an LB and possibly a NSM k8s-registry.
3. Check the proxy logs if they have received any notification about the lost LB NSE.

Expected behavior
Proxies should be notified through the NSM endpoint watcher about the lost LB NSE (and maybe via NSM heal as well about its unavailability).

Context

• Network Service Mesh: [e.g. v1.6.2]
• Meridio:1.1.0

Logs
Add logs here.

[zolug]

Could be (partially) related to networkservicemesh/sdk-k8s#456

[zolug]

Check again with NSM 1.13.2 and most recent Meridio.