Revert "MDEV-23753: SIGSEGV in Column_stat::store_stat_fields"

This reverts the commit 3b94309a but keeps the test

Because the fix is a hack that isn't supposed to do anything,
and relies on a side-effect of rnd_init inside ha_partition.

A different fix is coming up.

sql/sql_statistics.cc

@@ -2124,10 +2124,6 @@ int alloc_statistics_for_table(THD* thd, TABLE *table)
   ulonglong *idx_avg_frequency= (ulonglong*) alloc_root(&table->mem_root,
                                                sizeof(ulonglong) * key_parts);
 
-  if (table->file->ha_rnd_init(TRUE))
-    DBUG_RETURN(1);
-  table->file->ha_rnd_end();
-
   uint columns= 0;
   for (field_ptr= table->field; *field_ptr; field_ptr++)
   {