Rustfmt is bad at wrapping comments

For whatever reason, rustfmt keeps trying to wrap comments to way shorter
than we've told it to. This is boring, so let's tell rustfmt to go away
for now.

rustfmt.toml

@@ -6,7 +6,5 @@ imports_layout = "HorizontalVertical"
 use_field_init_shorthand = true
 use_try_shorthand = true
 format_code_in_doc_comments = true
-wrap_comments = true
 max_width = 115
-comment_width = 115
 use_small_heuristics = "max"