FindMatlab: Fix logic error when minimum version is not found Fix logic added by commit 7fdd5128b1 (FindMatlab: Fix version selection if a version is given, 2021-07-02, v3.22.0-rc1~66^2). Ensure that `_list_index` is always initialized to -1, akin to `list(FIND)` not finding a match. Issue: #22377