Fix activegate.customproperties.value when multi line string is used

[chrismuellner]

Description

When using a multi line string for customproperties.value in the values file, invalid yaml was generated by helm.

How can this be tested?

Use a values file that contains a multi line string in this section:

activeGate:
  capabilities:
  - kubernetes-monitoring
  customProperties:
    value: |
      [kubernetes_monitoring]
      key=value

Run the following command:

helm install dynatrace-operator config/helm/chart/default -f values.yaml --create-namespace -n dynatrace --dry-run

Checklist

• Unit tests have been updated/added
• PR is labeled accordingly