Default config values should not require entry in config file

[vigyasharma]

In general, if a config value does not need to be overridden, we should be able to skip it from config files and directly use code defaults.
The following configurations in code however, require an empty list to be provided, because of the way they are initialized. We should change this and give these configs, empty lists as default values.

  "muted-rcas": [],
  "muted-deciders": [],
  "muted-actions": [],