Update CREATE TRIGGER to use FUNCTION keyword

Since PG11 the syntax CREATE TRIGGER ... EXECUTE PROCEDURE is
deprecated. Change occurrences in the app to use CREATE TRIGGER ...
EXECUTE FUNCTION.

lib/gitlab/database/migration_helpers.rb

@@ -815,7 +815,7 @@ module Gitlab
         BEFORE INSERT OR UPDATE
         ON #{table}
         FOR EACH ROW
-        EXECUTE PROCEDURE #{trigger}()
+        EXECUTE FUNCTION #{trigger}()
         EOF
       end
 

lib/gitlab/database/schema_helpers.rb

@@ -25,7 +25,7 @@ module Gitlab
           CREATE TRIGGER #{name}
           #{fires} ON #{table_name}
           FOR EACH ROW
-          EXECUTE PROCEDURE #{function_name}()
+          EXECUTE FUNCTION #{function_name}()
         SQL
       end
 

spec/lib/gitlab/database/migration_helpers_spec.rb

@@ -712,7 +712,7 @@ RSpec.describe Gitlab::Database::MigrationHelpers do
             expect(model).to receive(:add_not_null_constraint).with(:users, :new)
             expect(model).to receive(:execute).with("UPDATE \"users\" SET \"new\" = cast_to_jsonb_with_default(\"users\".\"id\") WHERE \"users\".\"id\" >= #{user.id}")
             expect(model).to receive(:execute).with("DROP TRIGGER IF EXISTS #{trigger_name}\nON \"users\"\n")
-            expect(model).to receive(:execute).with("CREATE TRIGGER #{trigger_name}\nBEFORE INSERT OR UPDATE\nON \"users\"\nFOR EACH ROW\nEXECUTE PROCEDURE #{trigger_name}()\n")
+            expect(model).to receive(:execute).with("CREATE TRIGGER #{trigger_name}\nBEFORE INSERT OR UPDATE\nON \"users\"\nFOR EACH ROW\nEXECUTE FUNCTION #{trigger_name}()\n")
             expect(model).to receive(:execute).with("CREATE OR REPLACE FUNCTION #{trigger_name}()\nRETURNS trigger AS\n$BODY$\nBEGIN\n  NEW.\"new\" := NEW.\"id\";\n  RETURN NEW;\nEND;\n$BODY$\nLANGUAGE 'plpgsql'\nVOLATILE\n")
 
             model.rename_column_concurrently(:users, :id, :new, type_cast_function: 'cast_to_jsonb_with_default')

spec/support/helpers/trigger_helpers.rb

@@ -28,8 +28,6 @@ module TriggerHelpers
     expect(timing).to eq(expected_timing.to_s)
     expect(events).to match_array(Array.wrap(expected_events))
 
-    # TODO: Update CREATE TRIGGER syntax to use EXECUTE FUNCTION
-    # https://gitlab.com/gitlab-org/gitlab/-/issues/227089
     expect(definition).to match(%r{execute (?:procedure|function) #{fn_name}()})
   end