[BUG][data-prepper] Chart values should not have a default pipeline defined

[janhoy]

Describe the bug
The default values file has a demo pipeine defined. Even if you in your own values file define a my-pipeline, the demo simple-sample-pipeline will be deployed alongside it.

To Reproduce
Steps to reproduce the behavior:

1. Create a simple myvalues.yaml file with a pipelineConfig.config.my-pipeline defined
2. Install chart with -f myvalues.yaml
3. Look at the foo-data-prepper-pipeline secret - it contains both pipelines.

Expected behavior
You'd expect that the pipeline you configure is the only one installed.

You can achieve a blank slate today by using the existsingSecret property, but for simple pipelines the convenience of defining it in values file should achieve the same.

Chart Name
data-prepper

Screenshots

Host/Environment (please complete the following information):

• Helm Version: 3.16.3
• Kubernetes Version: 1.30.2

Additional context
Proposed fix is to ship chart without a configured pipeline. Alternatively use a noop pipeline that does nothing, to make the prepper not crash. Instead, ship an examples/ folder and move the simple-sample-pipeline example to a separate values file in that folder so users can do helm install myprepper opensearch/data-prepper -f example-values.yaml to test.

[prudhvigodithi]

[Triage]
I agree with you @janhoy can you start by commenting https://github.com/opensearch-project/helm-charts/blob/main/charts/data-prepper/values.yaml#L108 in the same values file, so that users can use that as example but actually would not be installed.
Thank you
@peterzhuamazon @TheAlgo

[janhoy]

We could comment the pipeline, but that would leave an empty config and prevent the prepper from starting at all after a helm install without parameters. Perhaps a way to achieve a dead simple working demo without providing your own pipeline could be to leave pipelineConfig.config empty in values, but provide a new value that people could set to enable a demo pipeline: helm install myPrepper opensearch/data-prepper --set pipelineConfig.demoPipeline=true. That would auto configure a demo pipeline in secret.yaml.

[janhoy]

See the pull requewst implementing my proposal. This is a cleaner way to enable demo pipeline.