Update infrequent polling sample to use BENIGN application error (#197)

* Update infrequent polling sample to use BENIGN application error

* formatting/linting

Author: THardy98

polling/test_service.py

@@ -2,6 +2,7 @@
 from typing import Counter
 
 from temporalio import activity
+from temporalio.exceptions import ApplicationError, ApplicationErrorCategory
 
 attempts = Counter[str]()
 ERROR_ATTEMPTS = 5
@@ -20,4 +21,10 @@ async def get_service_result(input):
     print(f"Attempt {attempts[workflow_id]} of {ERROR_ATTEMPTS} to invoke service")
     if attempts[workflow_id] == ERROR_ATTEMPTS:
         return f"{input.greeting}, {input.name}!"
-    raise Exception("service is down")
+    raise ApplicationError(
+        message="service is down",
+        # Set the error as BENIGN to indicate it is an expected error.
+        # BENIGN errors have activity failure logs downgraded to DEBUG level
+        # and do not emit activity failure metrics.
+        category=ApplicationErrorCategory.BENIGN,
+    )