feat: upgrade argocd image updater and leverage argocd application sources

[j-zimnowoda]

📌 Summary

• Upgrade argocd-image-updater
• Deploy workloads as Application instead of ApplicationsSets, so they are immediately visible in ArgoCD dashboard.
• Set argocd-application-image-updater to store updated tags in the values repo instead of the charts repo to adhere to the single source of truth rule.
• Get rid of the additional values property.

depends-on: linode/apl-api#832

🔍 Reviewer Notes

• This change leverages multiple Application sources instead of single source, so there are two values files for a given workload. One that is managed by user and the other that is managed by the argocd-application-image-updater
• The values are migrated automatically.
• upgrade script removes ApplicationSets without impacting Applications.
• user will be instructed to migrate content of k8s-deployment/.argocd-source-<team-name>-<workload-name>.yaml from charts repo to corresponding env/teams//workloads/.managed.yaml file and to delete the .argocd-source-<team-name>-<workload-name>.yaml

🧹 Checklist

• Code is readable, maintainable, and robust.
• Unit tests added/updated

[Ani1357]

Tested by upgrading existing cluster with running workloads. After the upgrade,the existing workload gets converted as expected in an application with 2 sources (values repo and charts repo) but since the old image sha was already saved in the charts repo, the image tag never gets updated. Deleting the k8s-deployment/.argocd-source-team-demo-<workload-name>.yaml solves it.

[j-zimnowoda]

Deleting the k8s-deployment/.argocd-source-team-demo-<workload-name>.yaml solves it.

Great finding! Thanks you.
For this use case I propose to add the upgrade instructions.