[kube-prometheus-stack] allow custom options for default grafana template

[Sherzod5]

Is your feature request related to a problem ?

Hi,
we are using kube-promethues-stack to monitor our clusters in thanos.
After some time we realised that grafana cannot display downsampling metrics. to fix this there is this option: max_source_resolution=auto and it should be added to customQueryParameters.

datasources:
- name: Prometheus
  type: prometheus
  uid: prometheus
  url: http://thanos-query-frontend:9090
  access: proxy
  isDefault: true
  jsonData:
    httpMethod: POST
    timeInterval: 30s
    timeout: 240
    customQueryParameters: "max_source_resolution=auto"

Describe the solution you'd like.

after that everything works fine. the question is that in kube-promethues-stack there is no place to add this parameter.

we even checked https://github.com/prometheus-community/helm-charts/blob/main/charts/kube-prometheus-stack/templates/grafana/configmaps-datasources.yaml this template but there is no such option there.
please add a possibility to add custom paramters to the helm chart

Describe alternatives you've considered.

Can you tell me how to add this parameter?
or is there any other key to solve this problem?

Additional context.

No response