Inconsistent inclusion of timestamps in logs

Logs of client connections include timestamp while logs of servers connections (to directory) do not.
This inconsistency result in either duplication of timestamp (if you add them externally) or lack of timestamp (if you don't).

See #3001

I'd suggest making it an option to include them, or never include them (relying on external tools to timestamp them).

Compare the client-connection and directory-server connection logging paths described in this issue, and review the related discussion in #3001. First determine whether timestamps should be optional or consistently delegated to external tools; done means both connection log types follow one documented timestamp policy without duplication or omission.

Written by the indexing model from the issue text.