[Anon] Mootlanders (1b): For the Mordheim Dataset, it seems like "unit group" doesn't correctly multiply the group cost/number

**Problem:**
For the Mordheim Dataset, it seems like "unit group" doesn't correctly multiply the group cost/number

**Expected:**
When I have a "Henchman group" of say, Halfling warriors, it takes up one slot, and it should be possible to increase the size of the group (most groups can contain 1-5 individual models). You can increase the number, but it currently does not seem to affect the cost of the warband, nor the warband strength.

**Additional Info:**

**List:** https://www.newrecruit.eu/app/list/1PRN3

Start by reproducing the issue with the linked Mordheim list and inspect the Mordheim Dataset entry for a unit group, focusing on how group size is represented. Compare the displayed group cost and warband strength at different sizes. Done means increasing the number of models updates both values correctly for applicable Henchman groups.

Written by the indexing model from the issue text.