Current implementation of CMakePresets create new kit from configurePresets. ConfigurePresets can't set debugger, thus kits are not fully complete and require manual change, after which QTC can create new toolkit (due to that difference). Also, from build_type and cmake flags possible only to set from configurePresets, which creat new kit for each required build types and defining custom configuration type not possible. 
Possible solution: use CMakePresets vendor field for selecting suitable tool kit and configurePresets use to set build configurations.