Remove NGINX container and runtime manager code from NGF deployment

[mpstefan]

Task to remove NGINX container and runtime management.

Dev Notes

• Existing calls to update NGINX are replaced with stubs to call to Agent with logs. This includes calls to the NGINX Plus API.
• Remove all code that manages NGINX runtime and writes files.
• Remove all references to the NGINX container, including the deployment and associated volumes.
• Update liveness probe to represent control plane status.
• Unit tests are updated or removed so that all unit tests still pass with removed NGINX management functionality.
• Should be able to deploy the control plane on its own.