f9ee1f7e introduced the hoisting of function settings as transaction-scoped
settings. However, this currently doesn't work with memory units, which are
case-sensitive according to the docs [1]. This removes the lowercasing of
values to make them work.
This is not added to the CHANGELOG, because this feature was not released, yet.
[1]: https://www.postgresql.org/docs/current/config-setting.html#CONFIG-SETTING-NAMES-VALUES