message: refactor(robot-server): Treat JSON v5 and earlier protocols as legacy
diff: @@ -3,7 +3,6 @@ import asyncio
  from concurrent.futures import ThreadPoolExecutor
  from functools import partial
  -from opentrons.config import feature_flags
  from opentrons.hardware_control import API as HardwareAPI
  from opentrons.protocols.api_support.types import APIVersion
  from opentrons.protocols.context.protocol_api.protocol_context import (
  @@ -35,10 +34,18 @@ from opentrons.protocols.types import (
  from .protocol_source import ProtocolSource
  +# The earliest Python Protocol API version ("apiLevel") where the protocol's simulation
  +# and execution will be handled by Protocol Engine, rather than the legacy machinery.
  +#
  +# Note that even when simulation and execution are handled by the legacy machinery,
  +# Protocol Engine still has some involvement for analyzing the simulation and
  +# monitoring the execution.
  LEGACY_PYTHON_API_VERSION_CUTOFF = APIVersion(3, 0)
  -# TODO(mc, 2021-09-21): remove this condition, cut off before 6 always
  -LEGACY_JSON_SCHEMA_VERSION_CUTOFF = 5 if feature_flags.enable_protocol_engine() else 6
  +
  +# The earliest JSON protocol schema version where the protocol is executed directly by
  +# Protocol Engine, rather than going through Python Protocol API v2.
  +LEGACY_JSON_SCHEMA_VERSION_CUTOFF = 6
  class LegacyFileReader:
  