pv_uni_display: Revert use of utf8_to_ov_or_die

This fixes #23089

Croaking when someone is trying to output a malformed UTF-8 sequence
turns out to be a bad idea.  That should have been obvious to me.

But instead of going back to the problematic utf8_to_uvchr_buf(), this
commit uses the non-croaking utf8_to_uv().

Croaking should not be done when at the user interface.  It makes sense,
for example, when things should have already been validated and there is
no good option to proceed.

Author: khwilliamson

utf8.c

@@ -4781,7 +4781,7 @@ Perl_pv_uni_display(pTHX_ SV *dsv, const U8 *spv, STRLEN len, STRLEN pvlim,
              break;
         }
 
-        u = utf8_to_uv_or_die(s, e, &next_len);
+        (void) utf8_to_uv(s, e, &u, &next_len);
         assert(next_len > 0);
 
         if (u < 256) {