reF(py): Update monitor_consumer to handle FilteredPayload

This is primarily a typing adjustment. Since we're not actually using
FilterStep we're never going to actualy get a FilteredPayload.

src/sentry/monitors/consumers/monitor_consumer.py

@@ -16,7 +16,7 @@
 from arroyo.processing.strategies.batching import BatchStep, ValuesBatch
 from arroyo.processing.strategies.commit import CommitOffsets
 from arroyo.processing.strategies.run_task import RunTask
-from arroyo.types import BrokerValue, Commit, Message, Partition
+from arroyo.types import BrokerValue, Commit, FilteredPayload, Message, Partition
 from django.db import router, transaction
 from sentry_kafka_schemas import get_codec
 from sentry_kafka_schemas.codecs import ValidationError
@@ -910,7 +910,10 @@ def process_batch(executor: ThreadPoolExecutor, message: Message[ValuesBatch[Kaf
             logger.exception("Failed to trigger monitor tasks")
 
 
-def process_single(message: Message[KafkaPayload]):
+def process_single(message: Message[KafkaPayload | FilteredPayload]):
+    if isinstance(message.payload, FilteredPayload):
+        return
+
     assert isinstance(message.value, BrokerValue)
     try:
         try: