IGNITE-24813 Java client: fix logging on server disconnect

[ptupitsyn]

• Handle exceptions in NettyClientMessageHandler to fix "An exceptionCaught() event was fired, and it reached at the tail of the pipeline"
• Improve logging

https://issues.apache.org/jira/browse/IGNITE-24813

[Copilot]

Pull request overview

This PR fixes the logging behavior when the server disconnects from a Java client connection. Previously, when a server closed the connection unexpectedly, exceptions would propagate to DefaultExceptionHandler, which logged them with full stack traces at WARN level. The fix introduces proper exception handling in NettyClientMessageHandler to catch and handle disconnection exceptions gracefully, logging them at DEBUG level instead.

Key changes:

• Added exceptionCaught handler to NettyClientMessageHandler to capture connection exceptions before they reach the default exception handler
• Changed onDisconnected parameter type from Exception to Throwable across the connection handling chain for broader exception coverage
• Moved connection closed logging to the close() method in TcpClientChannel to include exception details in the debug message

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
modules/client/src/main/java/org/apache/ignite/internal/client/io/netty/NettyClientMessageHandler.java	Added exceptionCaught method to handle connection exceptions and prevent propagation to default handler; refactored connection retrieval into helper method
modules/client/src/main/java/org/apache/ignite/internal/client/io/netty/NettyClientConnection.java	Changed onDisconnected parameter type from Exception to Throwable
modules/client/src/main/java/org/apache/ignite/internal/client/io/ClientConnectionStateHandler.java	Updated interface method signature to accept Throwable instead of Exception
modules/client/src/main/java/org/apache/ignite/internal/client/TcpClientChannel.java	Moved connection closed logging from onDisconnected to close() method and added exception message to debug log; updated method signatures
modules/client/src/test/java/org/apache/ignite/client/ConnectionTest.java	Added test to verify proper logging on server disconnect without exception stack traces
modules/client/build.gradle	Added awaitility test dependency for async condition waiting

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