Remove temp index on approval_project_rules

from approval_project_rules table. It was added
only to support a pos-deployment migration.

Changelog: other

db/migrate/20210819152723_remove_tmp_index_approval_project_rules_scanners.rb

+# frozen_string_literal: true
+
+class RemoveTmpIndexApprovalProjectRulesScanners < ActiveRecord::Migration[6.1]
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  INDEX_NAME = 'tmp_index_approval_project_rules_scanners'
+
+  def up
+    remove_concurrent_index_by_name :approval_project_rules, INDEX_NAME
+  end
+
+  def down
+    add_concurrent_index :approval_project_rules, :scanners, name: INDEX_NAME, using: :gin, where: "scanners @> '{cluster_image_scanning}'"
+  end
+end

db/schema_migrations/20210819152723

+b311fdb0a6e0e10ca3c67b9b2c3d920f8e735f0fd8398fdaa25853e14f88ae97
\ No newline at end of file

db/structure.sql

@@ -25903,8 +25903,6 @@ CREATE INDEX tmp_idx_deduplicate_vulnerability_occurrences ON vulnerability_occu
 
 CREATE INDEX tmp_idx_on_namespaces_delayed_project_removal ON namespaces USING btree (id) WHERE (delayed_project_removal = true);
 
-CREATE INDEX tmp_index_approval_project_rules_scanners ON approval_project_rules USING gin (scanners) WHERE (scanners @> '{cluster_image_scanning}'::text[]);
-
 CREATE INDEX tmp_index_namespaces_empty_traversal_ids_with_child_namespaces ON namespaces USING btree (id) WHERE ((parent_id IS NOT NULL) AND (traversal_ids = '{}'::integer[]));
 
 CREATE INDEX tmp_index_namespaces_empty_traversal_ids_with_root_namespaces ON namespaces USING btree (id) WHERE ((parent_id IS NULL) AND (traversal_ids = '{}'::integer[]));