Summary: Ref T7110. Listeners are now removed when clients close the connection to avoid stacking a never ending number of unused listeners.
Test Plan: Using `wscat` to connect to the Aphlict server; when closing the connection a 'Diconnected.' will appear in the logs and the number of active listeners is decreased by one.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: Korvin, epriestley
Maniphest Tasks: T7110
Differential Revision: https://secure.phabricator.com/D11634
4af1fd2a79