Rollup merge of #99508 - TaKO8Ki:avoid-symbol-to-string-conversion-in-BuiltinLintDiagnostics, r=compiler-errors

Avoid `Symbol` to `String` conversions

follow-up to #99342

compiler/rustc_resolve/src/diagnostics.rs

@@ -2603,9 +2603,9 @@ fn show_candidates(
                 .skip(1)
                 .all(|(_, descr, _, _)| descr == descr_first)
             {
-                descr_first.to_string()
+                descr_first
             } else {
-                "item".to_string()
+                "item"
             };
             let plural_descr =
                 if descr.ends_with("s") { format!("{}es", descr) } else { format!("{}s", descr) };