Remove nil value from variant's drugs array
Remove nil value from variant's drugs array

The array_agg aggregation function we use in the
app/datatables/variant_browse_table.rb select_query doesn't remove nil
values, which happends for variants that have evidence items that don't
have a drug.

genome/civic-server,genome/civic-server,genome/civic-server,genome/civic-server,genome/civic-server