only update fragmentation data for pages that are not lazily freed (#57907)

We are including data from lazily freed pages into this metric, which
makes it inaccurate.

Thanks @qinsoon for spotting it.

(cherry picked from commit d6fdbf5)

Author: d-netto

src/gc.c

@@ -1542,6 +1542,7 @@ static void gc_sweep_page(gc_page_profiler_serializer_t *s, jl_gc_pool_t *p, jl_
 
 done:
     if (re_use_page) {
+        gc_update_page_fragmentation_data(pg);
         push_lf_back(allocd, pg);
     }
     else {
@@ -1555,7 +1556,6 @@ static void gc_sweep_page(gc_page_profiler_serializer_t *s, jl_gc_pool_t *p, jl_
         }
     }
     gc_page_profile_write_to_file(s);
-    gc_update_page_fragmentation_data(pg);
     gc_time_count_page(freedall, pg_skpd);
     jl_ptls_t ptls = gc_all_tls_states[pg->thread_n];
     jl_atomic_fetch_add(&ptls->gc_num.pool_live_bytes, GC_PAGE_SZ - GC_PAGE_OFFSET - nfree * osize);