Support seperate ctype and collate for pg-upgrade

Using ctype as locale, as I believe you are more likely to want your character set as your locale default, than your sorting/comparison rules(collation)

Fixes: #4393 (closed)

I'm actually not sure for which reason that the users running into the issue have different LC_CTYPE than LANG or LC_COLLATE, whether some environment is defaulting to this, or not. But I do see from googling that setting collate to C for postgres was suggested to offer performance improvements (at least in the past). So I think this is a valid config to support either way. Especially when our initdb during reconfigure isn't opinionated about these.