(feat)managed-app: adds litmus to the list of managed apps

Add new application

• Application: LitmusChaos
• Chart: https://litmuschaos.github.io/litmus-helm/

New Application Checklist

• values.yaml matches one-click values.yaml (if also installable via GitLab UI)
• verify test added
• Merge request submitted to update the template project

Notes

LitmusChaos is a cloud-native chaos engineering framework that helps in running experiments on Kubernetes. Refer: https://github.com/litmuschaos/litmus

Ref: gitlab-org/gitlab#36789 (comment 432770661)