Fix authentication failure after updating pool_passwd and reload.

Fix authentication failure after updating pool_passwd and reload.

If pool_hba.conf is disabled, updating pool_passwd was not recognized
by pgpool child process even if pgpool reload was performed.  The
reload processing function check_config_reload() mistakenly assumed
that reopening pool_passwd was only necessary when enable_pool_hba is
on.

Backpatch-through: v4.1
Discussion: https://www.pgpool.net/pipermail/pgpool-general/2024-November/001944.html