Log submission failures via tracing level as these are expected

Motivation:

Sometimes submission of ops will fail if these are executed inline and return some error. This is expected and so we shouldn't log a warn message. That said it might still be useful to log these cases with trace level.

Modifications:

Log submission failures via tracing level

Result:

Use correct logging level that will not confuse people. This is a port of netty/netty#14671

Author: normanmaurer

transport-classes-io_uring/src/main/java/io/netty/incubator/channel/uring/IOUringSubmissionQueue.java

@@ -261,7 +261,8 @@ private int submit(int toSubmit, int minComplete, int flags) {
             if (ret < 0) {
                 throw new RuntimeException("ioUringEnter syscall returned " + ret);
             }
-            logger.warn("Not all submissions succeeded");
+            // some submission might fail if these are done inline and failed.
+            logger.trace("Not all submissions succeeded. Only {} of {} SQEs were submitted.", ret, toSubmit);
         }
         return ret;
     }