Added test to check if contained_channels get cleared when a channel is removed
Added test to check if contained_channels get cleared when a channel is removed

Factlink/factlink-core,daukantas/factlink-core,Factlink/factlink-core,Factlink/factlink-core,daukantas/factlink-core,daukantas/factlink-core,Factlink/factlink-core,daukantas/factlink-core