Revert "Change downstream projects configs to file_config (#1776)"

This reverts commit a4b4e10f0dbeedd7603a9e9722a68e90d794754f.

The commit breaks downstream: https://buildkite.com/bazel/bazel-at-head-plus-disabled/builds/1847#018bb630-70a4-46f1-9340-066445aa81da
1 file changed