Tweak logging statement levels

At present, for every JMS message sent there are the following 2
statements logged at info level:

- messageId in SQSMessageProducer#sendInternal
- shutting down executor in SQSSession#doClose

These result in excessive logging for systems that product a lot of JMS
messages and are really better fit for debug level.

Additionally, SQSMessageConsumer#doClose also has an equivalent logging
statement to one in SQSSession#doClose.

Finally, SQSSessionCallbackScheduler#run contains logging statement that
 logs exception at info level, which is better suited for warn level.

Author: vpavic

src/main/java/com/amazon/sqs/javamessaging/SQSMessageConsumer.java

@@ -224,7 +224,7 @@ void doClose() {
 
         try {
             if (!prefetchExecutor.isShutdown()) {
-                LOG.info("Shutting down {} executor", SQSSession.CONSUMER_PREFETCH_EXECUTOR_NAME);
+                LOG.debug("Shutting down {} executor", SQSSession.CONSUMER_PREFETCH_EXECUTOR_NAME);
                 // Shut down executor.
                 prefetchExecutor.shutdown();
             }

src/main/java/com/amazon/sqs/javamessaging/SQSMessageProducer.java

@@ -152,7 +152,7 @@ void sendInternal(SQSQueueDestination queue, Message rawMessage) throws JMSExcep
 
         SendMessageResponse sendMessageResult = amazonSQSClient.sendMessage(sendMessageRequest.build());
         String messageId = sendMessageResult.messageId();
-        LOG.info("Message sent to SQS with SQS-assigned messageId: {}", messageId);
+        LOG.debug("Message sent to SQS with SQS-assigned messageId: {}", messageId);
         // TODO: Do not support disableMessageID for now.
         message.setSQSMessageId(messageId);
 

src/main/java/com/amazon/sqs/javamessaging/SQSSession.java

@@ -405,7 +405,7 @@ void doClose() throws JMSException {
 
                 try {
                     if (executor != null) {
-                        LOG.info("Shutting down {} executor", SESSION_EXECUTOR_NAME);
+                        LOG.debug("Shutting down {} executor", SESSION_EXECUTOR_NAME);
 
                         executor.shutdown();
 

src/main/java/com/amazon/sqs/javamessaging/SQSSessionCallbackScheduler.java

@@ -143,7 +143,7 @@ public void run() {
                                 try {
                                     messageListener.onMessage(message);
                                 } catch (Throwable ex) {
-                                    LOG.info("Exception thrown from onMessage callback for message {}",
+                                    LOG.warn("Exception thrown from onMessage callback for message {}",
                                             message.getSQSMessageId(), ex);
                                     callbackFailed = true;
                                 } finally {