Remove DiagnosticBuilder::delay_as_bug_without_consuming.

The existing uses are replaced in one of three ways.
- In a function that also has calls to `emit`, just rearrange the code
  so that exactly one of `delay_as_bug` or `emit` is called on every
  path.
- In a function returning a `DiagnosticBuilder`, use
  `downgrade_to_delayed_bug`. That's good enough because it will get
  emitted later anyway.
- In `unclosed_delim_err`, one set of errors is being replaced with
  another set, so just cancel the original errors.

compiler/rustc_passes/src/errors.rs

@@ -1040,7 +1040,7 @@ impl<'a, G: EmissionGuarantee> IntoDiagnostic<'_, G> for BreakNonLoop<'a> {
                     // This error is redundant, we will have already emitted a
                     // suggestion to use the label when `segment` wasn't found
                     // (hence the `Res::Err` check).
-                    diag.delay_as_bug_without_consuming();
+                    diag.downgrade_to_delayed_bug();
                 }
                 _ => {
                     diag.span_suggestion(