The installer currently doesn't let you set the category collation for your wiki ($wgCategoryCollation). Under the "Advanced configuration" section of the installer, it should have a new option called "Category collation:" which let's you choose between (at least) uppercase, numeric, uca-default, uca-default-u-kn, and identity. If possible, it should only present the UCA options if you have the PHP intl library installed, and if it is installed, suggest uca-default-u-kn as the default choice. Otherwise, the default choice should be uppercase (which the current default in DefaultSettings.php). Each option should have some kind of description or explanation available. We may also want to make the actual option labels more readable, like "UCA with numeric" instead of "uca-default-u-kn".
If the wiki is set to a language other than English, and the PHP intl library installed, and the wiki language is one supported by MediaWiki's UCA collation, also make uca-XX and uca-XX-u-kn available as options, where XX is the language code.