rustc_ast_pretty: Remove PrintState::insert_extra_parens

It's no longer necessary after #79472

compiler/rustc_hir_pretty/src/lib.rs

@@ -138,9 +138,6 @@ impl std::ops::DerefMut for State<'_> {
 }
 
 impl<'a> PrintState<'a> for State<'a> {
-    fn insert_extra_parens(&self) -> bool {
-        true
-    }
     fn comments(&mut self) -> &mut Option<Comments<'a>> {
         &mut self.comments
     }