Fix `includeDescendants:false` returning nothing for subgroups

When includeDescendants:false is passed into a GraphQL query to get work items for a subgroup, no work items are returned even if there are work items that exist directly on that subgroup.

// returns nothing for a subgroup
query{
  group(fullPath:"flightjs/subgroup"){
    id
    workItems(includeDescendants:false){
      nodes {
        id
        title
      }
    }
  }
}

Acceptance criteria

• Including includeDescendants:false when getting work items for a subgroup returns work items directly associated with that subgroup

Latest Update

Based on the investigation performed as part of this issue here, querying work items at a group or subgroup level with includeDescendants:false works as expected in the backend. A follow-up issue was created to fix filtering work items by group or subgroup in the frontend.