Voltha timers rework

In Voltha release 2.8, we have a number of configurable variables used in various Voltha components which represent timers explicitly (e.g. timeout_request) or implicitly (e.g. max_connection_retries). When starting a Voltha container, it is not obvious which variable one should modify in order to influence the runtime environment.

This jira is to track the effort required to consolidate these timer variables into more meaningful names and standardize them across containers.