So I understand how Github actions works but I'm unable to find documentation on what exactly comprises the "App Service Build Service". I made an app service for a node.js application, and the first deployment I did defaulted to the app service build service. This did not create a .github/workflow file, it seems Azure is doing some behind-the-scenes magic to pull the repo on push. When I added a deployment slot for staging, that defaulted to Github Actions and did create a .github/workflow file on my staging branch.
I'd like to understand what exactly the "App Service Build Service" is, and is that preferable to Github Actions or not? I forget exactly where but I believe I read in the documentation what Github Actions was the recommended way to build, but the app service defaulted to App Service Build Service at least for the first deployment slot.