This removes the separate data files, which have been failing to load properly ([example](https://github.com/carbon-language/carbon-lang/runs/7957047892?check_suite_focus=true)). This one wasn't working previously, but hopefully will with these changes (and it might've also just been a pull_request_target issue, but the silent "Resource not accessible by integration" failures aren't great).
I accidentally put in one I'd considered, instead of the one I'd decided was probably the best fit, and the names are so similar I didn't notice.
NOTE: This still isn't totally working, but I think it will when we go public.
Jon Ross-Perkins
