We need to be able to expose and change the value of certain env variables available in the 3scale components, it can be currently achieved by patching the deployment config objects with the desired values for those env var but as it is not something supported by the 3scale operator and customizing those deployment config objects could result in some possible side effects.   

The request for this change comes as we are looking into rate limit the 3scale backend to allow support for customers self-managed APICast in RHOAM and to achieve this we need to make sure that internal requests from managed 3scale components are not rate limited. 

As it stands at the moment any self-managed APICast will fetch the backend route from the system app and the backend route is defined in the system app via two env variables:

• BACKEND_ROUTE for - internal communication
• BACKEND_PUBLIC_URL-  for external communication

The BACKEND_PUBLIC_URL env var is the one used on the APICast configs so self-managed APICasts can reach the backend via this route, 3scale operator only exposes BACKEND_ROUTE env var but we also need to be able to expose BACKEND_PUBLIC_URL env var and customize the values of those variables so we can define different routes for internal and external requests.