unitTest: Add `wait_for_removal_of` functions

test/unitTest/call/call.cpp

test/unitTest/call/conference.cpp

test/unitTest/common.h

test/unitTest/connectionManager/connectionManager.cpp

test/unitTest/conversation/conversation.cpp

...nitTest/conversationRepository/conversationRepository.cpp

test/unitTest/fileTransfer/fileTransfer.cpp

test/unitTest/ice/ice_sdp_parser.cpp

test/unitTest/media_control/media_control.cpp

test/unitTest/media_negotiation/media_negotiation.cpp

test/unitTest/syncHistory/syncHistory.cpp