pg_upgrade: Fix thinko in database info acquisition routine

pg_upgrade: Fix thinko in database info acquisition routine

When checking whether the major version supports per-database locale
providers, it was always looking at the version of the old cluster
instead of the cluster that was passed in.  This would lead to
failures to detect locale provider mismatches.

Reported-by: Marina Polyakova <m.polyakova@postgrespro.ru>
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/f385ba25e7f8be427b8c582e5cca7d79%40postgrespro.ru#515a31c5429d6d37ad1d5c9d66962a1e