Change pipe already registered log from error to warn level (snowflakedb#679)

Author: sfc-gh-rcheng

src/main/java/com/snowflake/kafka/connector/internal/SnowflakeSinkServiceV1.java

@@ -108,7 +108,7 @@ public void startTask(final String tableName, final TopicPartition topicPartitio
     String stageName = Utils.stageName(conn.getConnectorName(), tableName);
     String nameIndex = getNameIndex(topicPartition.topic(), topicPartition.partition());
     if (pipes.containsKey(nameIndex)) {
-      LOGGER.error("task is already registered, name: {}", nameIndex);
+      LOGGER.warn("task is already registered with {} partition", nameIndex);
     } else {
       String pipeName =
           Utils.pipeName(conn.getConnectorName(), tableName, topicPartition.partition());