Pass group IDs to MilestonesFinderrails5-milestone-groups

MilestonesFinder expects group ids in group_ids parameter (it does
`Array(params[:group_ids])`), but DashboardGroupMilestone.build_collection
was passing subquery instead. This doesn't work in rails 5 because
this evaluates into array of NULLs in the final query.

Because a separate query is used for loading group IDs both in rails4
and rails5 we can explicitly pass array of IDs to the MilestonesFinder
instead of subquery anyway.

`select.map` is used because `pluck` is failing with:
`undefined method `map' for #<Arel::Nodes::SqlLiteral...>`

1 files changed, 1 insertions, 1 deletions

diff --git a/app/models/dashboard_group_milestone.rb b/app/models/dashboard_group_milestone.rb
index 067e14dda1c..b6e4182d90f 100644
--- a/app/models/dashboard_group_milestone.rb
+++ b/app/models/dashboard_group_milestone.rb
@@ -13,7 +13,7 @@ class DashboardGroupMilestone < GlobalMilestone
   end
 
   def self.build_collection(groups)
-    MilestonesFinder.new(group_ids: groups.select(:id)).execute.map { |m| new(m) } # rubocop: disable CodeReuse/Finder
+    MilestonesFinder.new(group_ids: groups.select(:id).map(&:id)).execute.map { |m| new(m) } # rubocop: disable CodeReuse/Finder
   end
 
   override :group_milestone?