Minor (docs): Update how-to-use-the-playground.md document (#5955)

### What changes were proposed in this pull request?

Revert helm-chart related descriptions in
`docs/how-to-use-the-playground.md`.

### Why are the changes needed?

Make documentation match `README.md` of `apache/gravitino-playground` .

### Does this PR introduce _any_ user-facing change?

Yes, documentation is affacted.

### How was this patch tested?

Manually.

docs/how-to-use-the-playground.md

@@ -14,7 +14,6 @@ Depending on your network and computer, startup time may take 3-5 minutes. Once
 ## Prerequisites
 
 Install Git (optional), Docker, Docker Compose.
-Docker Desktop (or Orbstack) with Kubernetes enabled and helm CLI is required if you use helm-chart to deploy services.
 
 ## System Resource Requirements
 
@@ -50,82 +49,22 @@ git clone git@github.com:apache/gravitino-playground.git
 cd gravitino-playground
 ```
 
-#### Docker
-
-##### Start
-
-```
-./playground.sh docker start
-```
-
-##### Check status
-
-```shell 
-./playground.sh docker status
-```
-
-##### Stop playground
-
-```shell
-./playground.sh docker stop
-```
-
-#### Kubernetes
-
-Enable Kubernetes in Docker Desktop or Orbstack.
-
-In the project root directory, execute this command:
-
-```
-helm upgrade --install gravitino-playground ./helm-chart/ --create-namespace --namespace gravitino-playground --set projectRoot=$(pwd)
-```
-
-##### Start
+#### Start
 
 ```
-./playground.sh k8s start
+./playground.sh start
 ```
 
-##### Check status
+#### Check status
 
 ```shell 
-./playground.sh k8s status
-```
-
-##### Port Forwarding
-
-To access pods or services at `localhost`, you need to do these steps:
-
-1. Log in to the Gravitino playground Trino pod using the following command:
-
-```
-TRINO_POD=$(kubectl get pods --namespace gravitino-playground -l app=trino -o jsonpath="{.items[0].metadata.name}")
-kubectl exec $TRINO_POD -n gravitino-playground -it -- /bin/bash
-```
-
-2. Log in to the Gravitino playground Spark pod using the following command:
-
-```
-SPARK_POD=$(kubectl get pods --namespace gravitino-playground -l app=spark -o jsonpath="{.items[0].metadata.name}")
-kubectl exec $SPARK_POD -n gravitino-playground -it -- /bin/bash
-```
-
-3. Port-forward the Gravitino service to access it at `localhost:8090`.
-
-```
-kubectl port-forward svc/gravitino -n gravitino-playground 8090:8090      
-```
-
-4. Port-forward the Jupyter Notebook service to access it at `localhost:8888`.
-
-```
-kubectl port-forward svc/jupyternotebook -n gravitino-playground 8888:8888
+./playground.sh status
 ```
 
-##### Stop playground
+#### Stop playground
 
 ```shell
-./playground.sh k8s stop
+./playground.sh stop
 ```
 
 ## Experiencing Apache Gravitino with Trino SQL