Make `defaultIdleTimeout` configurable via configmap

[black-dragon74]

          `defaultIdleTimeout` was just a suggested name, I didn't see it was used elsewhere already. It was mostly about the capitalization of the name.

Whatever calls NewConnection() might be able to pass an alternative timeout. There should definitely be no configmap usage within these structs or package. It could be an improvement for a followup PR.

Originally posted by @nixpanic in #794 (comment)