[Feature] Remove PM2 as we don't use it anymore and only reference as dep

[evereq]

Check the whole project for any "pm2" and "@pm2/agent" references and remove those (e.g. in Dockerfiles and in code). We do NOT use PM2 anymore as we run all in Docker and Kubernetes and we do not recommend to use it as it changes license to AGPL and it might be problematic as dependency!

[emrankamil]

I want to work on this, but I need some clarifications: Have we replaced all the functionalities provided by PM2 with Docker and Kubernetes, ensuring that removing them won’t cause any potential issues?

[evereq]

@emrankamil we already pushed PR that make it, see history of messages.
PM2 was used long ago to run multiple node processes inside single instance.
If you are not using Docker Compose or Kubernetes or any other container infra, you probably need to run PM2 to be able to distribute load to multiple node processes. If you are using any of such platforms like k8s / Docker Compose or for example AWS ECS, you do NOT need it as those platforms run multiple docker containers (e.g. pods in k8s) and load balance.

We also will add PM2 support back at later point, but using plugins / separate repo etc. So those who need it, will be able to see how to use it.