Hi,
This is fine. We are not using mini variant of wpad and instead of it, we are using full-featured wpad.
I think you might miss one point from docs before installing any package, you need to do opkg update. I tried it and I see that package hostapd-utils package is there and that I am able to install it.
root@turris:~# opkg install hostapd-utils
Installing hostapd-utils (2019-08-08-ca8c2bd2-5) to root...
Downloading https://repo.turris.cz/hbl/omnia/packages/base/hostapd-utils_2019-08-08-ca8c2bd2-5_arm_cortex-a9_vfpv3-d16.ipk
Configuring hostapd-utils.