Enable ECS Server HA and promote agents Post ECS Installation

If you want to enable ECS Server for High Availability after installing ECS, then you must proceed with this section. If you do not want to enable ECS HA, you can safely ignore this section.

As a prerequisite, during the installation, you must have installed ECS with 1 master (with app_domain as Load Balancer URL) + agents. This allows you to promote Agents as masters.