Make an unique type name generation routine more resistant to name collisions

When Who What
2022-07-26 19:38:42 Tom Lane (tgl) Closed in commitfest 2022-07 with status: Committed
2022-07-26 19:19:01 Tom Lane (tgl) Added tgl as committer
2022-06-27 02:55:08 Andrei Lepikhov (lepikhov) Changed reviewers to Masahiko Sawada (masahikosawada)
2022-06-27 02:55:08 Andrei Lepikhov (lepikhov) Changed authors to Andrey Lepikhov (lepikhov), Dmitry Koval (d.koval)
2022-06-27 02:55:08 Andrei Lepikhov (lepikhov) Changed targetversion to 15
2022-06-27 02:54:24 Andrei Lepikhov (lepikhov) Attached mail thread b84cd82c-cc67-198a-8b1c-60f44e1259ad@postgrespro.ru
2022-06-27 02:54:23 Andrei Lepikhov (lepikhov) Created patch record