Fix for [pgpool-general: 7896] Possible race condition..

Fix for [pgpool-general: 7896] Possible race condition..

Watchdog does not allow the remote nodes reported lost by life-check to rejoin
the cluster until the life-check process confirms the existence of life in the
previously lost nodes. This is good enough except for the case when the
(lost by life-check) node tries to rejoin the cluster after it was restarted
(Pgpool-II service restarted).
What happens is the cluster keeps rejecting the restarted node because
the cluster's life-check doesn't agree while the restarted node's life-check
waits to be added to cluster before it can start sending the heart-beats.

The fix is to allow the previously lost remote node become the part of the
cluster after restart, no matter the lost-reason.

Issue report:
https://www.pgpool.net/pipermail/pgpool-general/2021-November/007954.html