These files are auto-generated and will never be clang-formatted, so the comments are just noise.
Meanwhile they introduce a moral hazard, that new contributors see all these clang-format comments in the repo and think they set a precedent for clang-format comments in *non*-generated parts of the codebase.
(I propose also two followups: one to remove clang-format comments from the human-written parts of the codebase, and one to disable the check-format step in libcxx/utils/ci/run-buildbot — it seems to be causing vastly more harm than benefit.)