Dataflow distribution metrics returns additional counters

Dataflow changed name endings in metrics from [MAX], [MIN], [COUNT] and [MEAN] into _MAX, _MIN, _COUNT and _MEAN. Because of that Dataflow returns additional counter metrics with those suffixes while collecting distribution metrics.

To ignore counters with new names it is required to change the suffixes in dataflow_metrics.py here https://github.com/apache/beam/blob/6737a09b39949a9071c9b06f36b31eda1491895f/sdks/python/apache_beam/runners/dataflow/dataflow_metrics.py#L156