Remove useless tidy-alphabetical markers.

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

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};