misc: cleanup some unused code and code smells

src/client/configurationmanager.cpp

src/connectivity/ice_transport.cpp

src/connectivity/ice_transport.h

src/connectivity/security/certstore.cpp

src/jamidht/swarm/routing_table.cpp

src/jamidht/swarm/routing_table.h

src/media/media_attribute.cpp

src/sip/sipaccount.cpp