Remove logged warnings for maintenance mode check (#4396)

Every time a request hits the app, a `MAINTENANCE_MODE` S3 warning is thrown when it is off. This is going to flood the logs with a not-so-needed warning.

backend/config/middleware.py

@@ -12,7 +12,7 @@ def is_maintenance_on():
     Get current status of maintenance mode.
     """
 
-    return file_exists(S3_FILENAME)
+    return file_exists(S3_FILENAME, show_warning=False)
 
 
 def change_maintenance(enabled):
@@ -37,7 +37,7 @@ def change_maintenance(enabled):
 
     # turn off.
     else:
-        if file_exists(S3_FILENAME):
+        if file_exists(S3_FILENAME, show_warning=False):
             s3_client.delete_object(
                 Bucket=settings.AWS_PRIVATE_STORAGE_BUCKET_NAME, Key=S3_FILENAME
             )

backend/dissemination/file_downloads.py

@@ -38,7 +38,7 @@ def get_filename(report_id, file_type):
             raise Http404()
 
 
-def file_exists(filename):
+def file_exists(filename, show_warning=True):
     # this client uses the internal endpoint url because we're making a request to S3 from within the app
     s3_client = boto3_client(
         service_name="s3",
@@ -57,7 +57,8 @@ def file_exists(filename):
 
         return True
     except ClientError:
-        logger.warn(f"Unable to locate file {filename} in S3!")
+        if show_warning:
+            logger.warn(f"Unable to locate file {filename} in S3!")
         return False