fix(preprod): Fix temporary visibility problem with preprod

`rxEnvironmentMatch` is currently broken in encore-ui, such that
if you're in a `preprod` environment, it won't return `true`
for `('unified-preprod' | rxEnvironmentMatch)` (but it should
return `true`)

This is a temporary workaround. We'll do an encore-ui update afterwards
that fixes `rxEnvironmentMatch`