tracking: Update Helm charts for 26.3.0

[sbernauer]

Pre-Release Demo Chart Updates

There are a bunch of demos which directly use Helm charts to install some required parts of the
demo / stack. These charts need updating before we start testing the stable to nightly upgrade.

Most of the charts are located in the stacks/_templated folder. Additional folders are:
stacks/observability and stacks/signal-processing. It is recommended to search for releaseName
to find all referenced charts.

Best-effort helper script

There is a best-effort helper script which might help you: .scripts/update_helm_charts.py.
Please read the warnings it prints on startup and keep them in mind.

Update Instructions

These instructions help to update the charts:

# List all available repos
helm repo list

Make sure, you have the following repos added:

NAME                  URL
bitnami               https://charts.bitnami.com/bitnami
stackable-dev         https://repo.stackable.tech/repository/helm-dev/
stackable-stable      https://repo.stackable.tech/repository/helm-stable/
timescale             https://charts.timescale.com/
prometheus-community  https://prometheus-community.github.io/helm-charts
vector                https://helm.vector.dev
grafana               https://grafana.github.io/helm-charts
jaeger                https://jaegertracing.github.io/helm-charts
opentelemetry         https://open-telemetry.github.io/opentelemetry-helm-charts
jupyterhub            https://jupyterhub.github.io/helm-chart/
opensearch            https://opensearch-project.github.io/helm-charts

To add any that are missing, run:

helm repo add bitnami https://charts.bitnami.com/bitnami --force-update

Then make sure you have the latest indexes:

helm repo update

Next, search for the latest version of the desired chart, eg grafana/grafana:

# Display the latest versions of a chart
$ helm search repo grafana/grafana --versions | head -5
NAME             CHART VERSION  APP VERSION
grafana/grafana  8.6.0          11.3.0
grafana/grafana  8.5.12         11.3.0
grafana/grafana  8.5.11         11.3.0
grafana/grafana  8.5.10         11.3.0

Use the applicable chart version displayed to replace the current one in the YAML files. Make sure
to add the app version in the comments. Eg:

version: 3.2.1 # 1.2.3

Take a look at previous PRs for additional guidance, eg. #119.