I don't think it fits under that at all, and I find that when people do see it that way it gets an entirely different treatment. "Manual testing" is an activity

I don't think it fits under that at all, and I find that when people do see it that way it gets an entirely different treatment. "Manual testing" is an activity you do when you are thinking about how the product works. "Dogfooding" is a culture of using the product in order to achieve other tasks that you really wanted to get done.