Fix pgbench's exit status and log messages for connection failures

When Who What
2021-11-02 14:12:47 Fujii Masao (masaofujii) Closed in commitfest 2021-11 with status: Committed
2021-10-05 15:47:44 Fujii Masao (masaofujii) Added masaofujii as committer
2021-10-01 06:26:05 Michael Paquier (michael-kun) Closed in commitfest 2021-09 with status: Moved to next CF
2021-08-03 02:19:07 Masahiko Sawada (masahikosawada) Closed in commitfest 2021-07 with status: Moved to next CF
2021-07-18 14:38:00 Yugo Nagata (yugo.nagata) Changed targetversion to stable
2021-06-30 05:50:37 Yugo Nagata (yugo.nagata) Changed authors to Fabien Coelho (calvin), Yugo Nagata (yugo.nagata)
2021-06-30 05:50:10 Yugo Nagata (yugo.nagata) Attached mail thread TYCPR01MB5870057375ACA8A73099C649F5349@TYCPR01MB5870.jpnprd01.prod.outlook.com
2021-06-30 05:50:09 Yugo Nagata (yugo.nagata) Created patch record