While looking at backporting [[https://github.com/bitcoin/bitcoin/pull/24196 | core#24196]], I noticed that the offending code was already changed in D359 (`unsigned int` -> `size_t`) and fixed in D1528 (removal of the
`for (size_t j = tx.vin.size(); j-- > 0;)` loop)
Removing the file-wide suppression means that new UB can now be detected.