Break out mock of pymodbus return from mock_modbus to new fixture (#55063)

* Remove unused mock_modbus.

* Break out mock pymodbus return values.

* Review comments.

tests/components/modbus/test_climate.py

@@ -86,7 +86,7 @@ async def test_config_climate(hass, mock_modbus):
         ),
     ],
 )
-async def test_temperature_climate(hass, expected, mock_modbus, mock_do_cycle):
+async def test_temperature_climate(hass, expected, mock_do_cycle):
     """Run test for given config."""
     assert hass.states.get(ENTITY_ID).state == expected