Pre-Prod: Adapt & install prometheus + prometheus-additional-manifests apps

[LukasCuperDT]

DESCRIPTION:
The purpose of this task is to adapt/fix/configure the prometheus and prometheus-additional-manifests application to the Pre-Prod environment, by the use of ArgoCD Application manifest. Your new working branch should be created from branch Helm_charts_restructure&Pre-Prod_setup of this repository and pull request should be targeting exactly to the same branch.

SCOPE:

• Adapt, configure, install and test the deployment of prometheus application to the Pre-Prod env by help of ArgoCD's application manifest. The values file containing the argocd applications can be found under path github/system-config/kubernetes/helm_charts/local/argo-cd/values/preprod/values-argocd-applications.yaml within branch Helm_charts_restructure&Pre-Prod_setup .
• The prometheus & prometheus-additional-manifests applications can be found as a commented out code in github/system-config/kubernetes/helm_charts/local/argo-cd/values/preprod/values-argocd-applicationSets.yaml, form where it needs to be migrated to github/system-config/kubernetes/helm_charts/local/argo-cd/values/preprod/values-argocd-applications.yaml. As the applicationSet is a set of two apps, extract also prometheus-additional-manifests application, so the configuration can be bound together.

TASKS:

• Adapt, configure, install and test the deployment of prometheus and prometheus-additional-manifests
• Maintain the clear separation of prod and preprod env of the values file or kustomization structure
• Deploy the application by the use of ArgoCD's application manifest
• Create descriptive PR, containing the general information of what has been change/done

ACCEPTANCE CRITERIA:
[ x ] prometheus and prometheus-additional-manifests application is present in ArgoCD's pre-prod env and fully functional, including best security practices (no hardcoded credentials, private links, security contexts of the application improved, etc.)
[ x ] Raised descriptive PR with proposed changes to the branch Helm_charts_restructure&Pre-Prod_setup