pg_upgrade: force timeline 1 in the new cluster

pg_upgrade:  force timeline 1 in the new cluster

Previously, this prevented promoted standby servers from being upgraded
because of a missing WAL history file.  (Timeline 1 doesn't need a
history file, and we don't copy WAL files anyway.)

Report by Christian Echerer(?), Alexey Klyukin

Backpatch through 9.0