Merge branch '215147-drop-feature-flag' into 'master'

Drop feature flag: import_bulk_inserts

Closes #215147

See merge request gitlab-org/gitlab!30057

changelogs/unreleased/215147-drop-feature-flag.yml

+---
+title: 'Project import queries are now partially batched'
+merge_request: 30057
+author:
+type: performance

lib/gitlab/import_export/relation_tree_restorer.rb

@@ -37,9 +37,7 @@ module Gitlab
           ActiveRecord::Base.no_touching do
             update_params!
 
-            bulk_inserts_enabled = @importable.class == ::Project &&
-              Feature.enabled?(:import_bulk_inserts, @importable.group, default_enabled: true)
-            BulkInsertableAssociations.with_bulk_insert(enabled: bulk_inserts_enabled) do
+            BulkInsertableAssociations.with_bulk_insert(enabled: @importable.class == ::Project) do
               fix_ci_pipelines_not_sorted_on_legacy_project_json!
               create_relations!
             end