Tuning Envoys: Adjust Istio Idle Timeout in UDS Core

[cmwylie19]

Related to #745

With regard to the Kubernetes Watch flakiness it was suggested to try adjusting the idleTimeout in Istio to see if that plays any role keeping the connections alive.

Background: The idleTime determines the duration a connection can be idle before being terminated by the proxy.

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: timeout-test
  namespace: istio-system
spec:
  configPatches:
  - applyTo: NETWORK_FILTER
    match:
      context: ANY # EVERYWHERE!
      listener:
        filterChain:
          filter:
            name: "envoy.filters.network.http_connection_manager"
    patch:
      operation: MERGE
      value:
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
          common_http_protocol_options:
            idle_timeout: "3h" # Increased from 1 hour

Definition of done:

• Deploy UDS Core with Pepr <= 0.31.0 (Pre-Informer to make sure results are not skewed)
• Crank up neuvector the CronJob to run every minute
• Deploy this EnvoyFilter for the whole mesh
• Document and present results

CC: @blancharda

Related External Issue: istio/istio#50089

[cmwylie19]

Unfortunately tuning the Envoy's idleTimeout has not played a factor.