Change CTFE backtraces to use note instead of label to preserve their order

labels are reordered within the file in which they are reported, which can mess up the stack trace

compiler/rustc_const_eval/src/const_eval/error.rs

@@ -123,14 +123,14 @@ impl<'tcx> ConstEvalErr<'tcx> {
                 // Helper closure to print duplicated lines.
                 let mut flush_last_line = |last_frame, times| {
                     if let Some((line, span)) = last_frame {
-                        err.span_label(span, &line);
+                        err.span_note(span, &line);
                         // Don't print [... additional calls ...] if the number of lines is small
                         if times < 3 {
                             for _ in 0..times {
-                                err.span_label(span, &line);
+                                err.span_note(span, &line);
                             }
                         } else {
-                            err.span_label(
+                            err.span_note(
                                 span,
                                 format!("[... {} additional calls {} ...]", times, &line),
                             );