Configuration should be primarily through application.yaml and not environment variables

[jessesimpson36]

Currently, we configure the applications via env vars.
We should move to application config like what we did in Helm (here is an example for Optimize)

Most, if not all, env vars follow the Sprint Boot convention, so SPRING_CONFIG_NAME=xyz represents the following YAML:

spring:
  config:
    name: xyz

Just be careful of how entry point scripts may alter env vars, like Zeebe entry point altering ZEEBE_GATEWAY_NETWORK_HOST