Fix stale comment in Netty4Utils

We previously named the thread using a frame from the stack trace, but
this was removed to simplify the code here. However, the comment
explaining this was left behind and this commit cleans that up.

modules/transport-netty4/src/main/java/org/elasticsearch/transport/netty4/Netty4Utils.java

@@ -133,8 +133,7 @@ public class Netty4Utils {
              * Here be dragons. We want to rethrow this so that it bubbles up to the uncaught exception handler. Yet, Netty wraps too many
              * invocations of user-code in try/catch blocks that swallow all throwables. This means that a rethrow here will not bubble up
              * to where we want it to. So, we fork a thread and throw the exception from there where Netty can not get to it. We do not wrap
-             * the exception so as to not lose the original cause during exit, so we give the thread a name based on the previous stack
-             * frame so that at least we know where it came from (in case logging the current stack trace fails).
+             * the exception so as to not lose the original cause during exit.
              */
             try {
                 // try to log the current stack trace