Parsers: instantiate property parser for vector<vector<int>>

We already have a parser for vector<vector<double>> so it makes sense to do the same for int.

changed milestone to %v39r0

mentioned in commit fwinkl/athena@18af9f97

mentioned in merge request atlas/athena!74367 (merged)

approved this merge request

merged

mentioned in commit e2e052a9

mentioned in commit fwinkl/athena@936fdf3c