fix(api): Do not pass loop arg to subproc (#14570)

asyncio subprocess used to need loop; now it doesn't. For a
minimum-affected fix, just don't pass loop to the subprocess invocations
while keeping it in the top level environment.

Closes RQA-2417

api/src/opentrons/hardware_control/modules/update.py

@@ -34,7 +34,6 @@ async def update_firmware(
         kwargs: Dict[str, Any] = {
             "stdout": asyncio.subprocess.PIPE,
             "stderr": asyncio.subprocess.PIPE,
-            "loop": loop,
         }
         successful, res = await module.bootloader()(
             flash_port_or_dfu_serial, str(firmware_file), kwargs

api/tests/opentrons/hardware_control/test_modules.py

@@ -240,7 +240,6 @@ def async_return(result):
     bootloader_kwargs = {
         "stdout": asyncio.subprocess.PIPE,
         "stderr": asyncio.subprocess.PIPE,
-        "loop": loop,
     }
 
     upload_via_avrdude_mock = mock.Mock(