Fix remote cluster sync timeout issue

[SpecialYang]

Currently, the informerInit marker doesn't work for remote cluster sync timeout case. Remove it and use the initialSync marker.

CC @hzxuzhonghu

[istio-policy-bot]

🤔 🐛 You appear to be fixing a bug in Go code, yet your PR doesn't include updates to any test files. Did you forget to add a test?

Courtesy of your friendly test nag.

[hzxuzhonghu]

the informerInit marker doesn't work for remote cluster sync timeout case

Can you elaborate on this

[SpecialYang]

The HasSync method only cares about the var initialSync. The var informerInit doesn't effect on the logic of HasSync. Additionally, we alway set the informerInit as true before execution of WaitForCacheSync. So this var is useless and doesn't work for the cluster sync timeout case.

istio/pilot/pkg/serviceregistry/kube/controller/controller.go

Lines 837 to 854 in 8548a35

	func (c *Controller) Run(stop <-chan struct{}) {
	if c.opts.SyncTimeout != 0 {
	time.AfterFunc(c.opts.SyncTimeout, func() {
	if !c.informerInit.Load() {
	log.Warnf("kube controller for %s initial sync timed out", c.opts.ClusterID)
	c.informerInit.Store(true)
	}
	})
	}
	st := time.Now()
	if c.opts.NetworksWatcher != nil {
	c.opts.NetworksWatcher.AddNetworksHandler(c.reloadNetworkLookup)
	c.reloadMeshNetworks()
	c.reloadNetworkGateways()
	}
	c.informerInit.Store(true)
	kubelib.WaitForCacheSync(stop, c.informersSynced)

[hzxuzhonghu]

Can you add a release note, it need to be backported

[SpecialYang]

/retest

[SpecialYang]

/retest

[ericvn]

Release Notes LGTM

[SpecialYang]

/retest