fix(docs): Update getting-started script pre-26.3.0

[Techassi]

Check and Update Getting Started Script

Part of stackabletech/issues#826

This getting-started script was technically fine as is (it ran through without any issues), but I still opted to include both waiting conditions, because it generally a good thing to do going forward.

[adwk67]

This hangs when using the helm install (stackablectl works fine):

Events:
  Type     Reason            Age                   From               Message
  ----     ------            ----                  ----               -------
...
MountVolume.SetUp failed for volume "pvc-f096ca69-82f2-43c4-8a6f-9e02c103f8bf" : rpc error: code = Unavailable desc = listener has no addresses yet
  Warning  FailedMount       41s (x9 over 4m50s)   kubelet            MountVolume.SetUp failed for volume "pvc-9de1bb0c-f73a-40b3-9671-ea9d83f68923" : rpc error: code = FailedPrecondition desc = failed to parse pod details: PodListeners.v1alpha1.listeners.stackable.tech/pod-7d2401dc-ca8a-45fa-a5a5-a34881a68726.default has no addresses for listener discovery-service-listener yet

I'll try again

[adwk67]

This hangs when using the helm install (stackablectl works fine):
...

OK, I need to helm install the listener-op with --set preset=stable-nodes on kind

Fix

Either change
helm install --wait listener-operator oci://oci.stackable.tech/sdp-charts/listener-operator --version 0.0.0-dev
to append --preset=stable-nodes in getting_started.sh/.sh.j2 or change discoveryServiceListenerClass: external-stable --> external-unstable in opensearch.yaml.