BulkImports: Import milestone `iid`

Problem

Currently the BulkImports::Groups::Pipelines::MilestonesPipeline is not importing the milestone iid field, because it is not exposed in the GraphQL API.

Proposed solution

After exposing the iid on the GraphQL API (#326129 (closed)), add it to the query in BulkImports::Groups::Graphql::GetMilestonesQuery

added to epic &4619 (closed)

changed milestone to %13.11

added Category:Importers GraphQL Next Up backend devopsmanage sectiondev workflowready for development + 1 deleted label

set weight to 2

marked this issue as related to #326129 (closed)

marked this issue as related to #324731 (closed)

added [deprecated] Accepting merge requests label

mentioned in issue #324731 (closed)

added workflowblocked label and removed workflowready for development label

added workflowin dev label and removed workflowblocked label

assigned to @kassio

removed [deprecated] Accepting merge requests label

mentioned in commit 3848b862

mentioned in commit 713127dd

mentioned in commit c9b9cb4e

mentioned in merge request !58107 (merged)

added workflowin review label and removed workflowin dev label

mentioned in commit dd40a4be

added workflowverification label and removed workflowin review label

closed

added workflowproduction label and removed workflowverification label

added Importer:Direct Transfer label

added groupimport and integrate label and removed 1 deleted label