Ceph » rgw

currently, connections never expire, the existing "disconnect()" API is not used from inside the RGW.
since multiple topics may be using the same kafka broker, we cannot disconnect based on topic deletion.
not deleting the connection may create a problem for the case when a kafka broker is decommissioned and the RGW keep on trying to reconnect to it, emitting error log messages which may be confusing for the user.

• remove the disconnect() API including code handling the marked_for_deletion flag
• check librdkafka configuration [1] to set a timeout on connections. as well as the callback to remove it from the connection list

[1] https://github.com/edenhill/librdkafka/blob/master/CONFIGURATION.md