All our sceneries in P3D 4+ DO NOT use the scenery.cfg, they use only the add-on.xml method. Our scenery installers in P3D4+ DO NOT read, write or modify the scenery.cfg in any way so, the only possible reason why you have an FSDT Los Angeles in the scenery.cfg, is that you have added it yourself, and made some kind of mistake.
Perhaps you copied an old scenery.cfg from an older installation ? In that case, you can just remove the area and, you'll notice that, if you install KLAX using our installer, it won't add anything to the scenery.cfg, because it's not required.