[SDP-1236] Fix SDP helm chart defaults and minimal-values

[marwen-abid]

• Small fixes when running this Chart using the minimal-values.yaml
• Changed default background job processing to Scheduler instead of Kafka for an easier minimal setup
• Fixed Anchor secrets that were being generated from the ConfigMap

Testing this locally

1. Pre-requisites

   1. docker desktop
   2. kubectl in command line
   3. helm in command line

2. Enable Kubernetes in docker-desktop settings

3. Switch to docker-desktop kubernetes context

   kubectl config use-context docker-desktop

4. Install the Stellar helm chart

• Add the Stellar helm repository

  helm repo add stellar https://helm.stellar.org/charts

• Copy minimal values

  curl -LJO https://raw.githubusercontent.com/stellar/stellar-disbursement-platform-backend/develop/helmchart/sdp/minimal-values.yaml

• Customize minimal values

5. Install SDP

   helm install sdp -f minimal-values.yaml stellar/stellar-disbursement-platform