timeoutSec not enforced on Windows and

[prods]

Problem Description
When timeoutSec is set on a DAG step, processes that exceed the timeout should be forcibly terminated. However, on Windows, some processes would continue running for hours even when timeoutSec was set (e.g., to 900 seconds).

Root Cause
The issue had two components:

1. Blocking cmd.Wait(): The commandExecutor.Run() method blocked indefinitely on cmd.Wait() without listening to context cancellation. When the timeout expired, the process would not be killed because the code was stuck waiting for Wait() to return.

2. Incomplete process termination on Windows: The Windows KillProcessGroup() function only killed the immediate process, leaving child processes (subprocess tree) orphaned and running.

[prods]

This issue is resolved by PR 1635