Replace the git submodule with directly tracked files so that `git commit .` no longer fails with 'does not have a commit checked out'. Removed .github/ from the vendored copy since upstream CI workflows are not needed here.
Replace the git submodule with directly tracked files so that `git commit .` no longer fails with 'does not have a commit checked out'. Removed .github/ from the vendored copy since upstream CI workflows are not needed here.