[Bug]: Two threads leak after executed Pipeline&Workflow

[shlxue]

Apache Hop version?

2.13.0

Java version?

17.0.13

Operating system

macOS

What happened?

When execute a pipeline or workflow.
Some ui elements and dynamic threads were created by HopGuixxxDelegate classes,
but some thread don’t clean after closed the pipeline.

1. open a pipeline & executed
2. close the pipeline after completed the execution
3. two threads leak
4. repeat 1-3: again leak…

[shlxue]

Thread stack list:

[shlxue]

As a dynamically created UI element (potentially containing UI elements, threads, or timers), HopGuiXXXGraph needs to clean up its created object instances at appropriate times.

There are two primary scenarios where these instances should be released:

1. When the UI is disposed/destroyed
2. Upon completion of the pipeline and workflow execution.

Specifically for Timers, related active tasks should be stopped once the execution is finished.

We could potentially add an onExecutionFinished callback on HopGuiXxxDelegate to ensure timely cleanup of timer tasks.
Otherwise, even after the current pipeline execution completes, these timer tasks would continue to execute UI refreshes at a high frequency.