Remove --print unversioned-files from rustdoc

This flag isn't needed anymore. See #83784.

src/librustdoc/html/render/mod.rs

@@ -33,7 +33,6 @@ mod print_item;
 mod write_shared;
 
 crate use context::*;
-crate use write_shared::FILES_UNVERSIONED;
 
 use std::collections::VecDeque;
 use std::default::Default;