MDL-40913 core_message: replaced the 'add contact' add_to_log call with an event
MDL-40913 core_message: replaced the 'remove contact' add_to_log call with an event
MDL-40913 core_message: replaced the 'block contact' add_to_log call with an event
MDL-40913 core_message: replaced the 'unblock contact' add_to_log call with an event