Remove useless `tidy-alphabetical` markers.

rustfmt already sorts `use` declarations within the same group.

compiler/rustc_fs_util/src/lib.rs

@@ -1,9 +1,7 @@
-// tidy-alphabetical-start
 use std::ffi::CString;
 use std::fs;
 use std::io;
 use std::path::{absolute, Path, PathBuf};
-// tidy-alphabetical-end
 
 // Unfortunately, on windows, it looks like msvcrt.dll is silently translating
 // verbatim paths under the hood to non-verbatim paths! This manifests itself as

compiler/rustc_lint_defs/src/lib.rs

@@ -1,4 +1,3 @@
-// tidy-alphabetical-start
 pub use self::Level::*;
 use rustc_ast::node_id::NodeId;
 use rustc_ast::{AttrId, Attribute};
@@ -15,7 +14,6 @@ use rustc_span::edition::Edition;
 use rustc_span::symbol::MacroRulesNormalizedIdent;
 use rustc_span::{sym, symbol::Ident, Span, Symbol};
 use rustc_target::spec::abi::Abi;
-// tidy-alphabetical-end
 
 use serde::{Deserialize, Serialize};