MDEV-21027 Assertion `part_share->auto_inc_initialized || !can_use_for_auto_inc_init()' failed in ha_partition::set_auto_increment_if_higher

ha_partition::set_auto_increment_if_higher expects
part_share->auto_inc_initialized is true or can_use_for_auto_inc_init()
is false (but as the comment of this method says, it returns false
only if we use Spider engine with DROP TABLE or ALTER TABLE query).
However, part_share->auto_inc_initialized becomes true only after all
partitions are opened (since 6dce6aec).

Therefore, I added a conditional expression in order to read all
partitions when we execute REPLACE on a table that has an
AUTO_INCREMENT column.           

Reviewed by: Nayuta Yanagisawa
Reviewed by: Alexey Botchkov