Consider replacing pulsar with RabbitMQ

[rhinoman]

Originally thought I might need the higher throughput of Pulsar (or Kafka) for moving data through the system, but since I've landed on using direct calls between plugins and services to move data, I've been using Pulsar for async message passing only.

The complexity of Pulsar is thus probably unnecessary, consider moving to RabbitMQ or perhaps ActiveMQ/Artemis for async messaging needs.