Intermittent `503 connection termination` errors when resuming suspended actors

## Expected Behavior
Expected to get actual response from the server running in the actor.

## Actual Behavior
```
HTTP 503 | upstream connect error or disconnect/reset before headers. reset reason: connection termination
```

## Steps to Reproduce the Problem

1. Create actortemplates and actors. I was using
```
./hack/install-ate.sh --deploy-demo-multi-template
kubectl ate create actor f1 --template ate-demo-multi-template-fspersist/fspersist
kubectl port-forward -n ate-system svc/atenet-router 8000:80 # leave running
```
1. Suspend and then resume actors right away
```
for round in $(seq 1 20); do
kubectl ate suspend actor f1
curl -s -H "Host: f1.actors.resources.substrate.ate.dev" http://localhost:8000
done
```
1. Observe intermittent error messages `upstream connect error or disconnect/reset before headers. reset reason: connection termination`