fix(harness): drain local shell output while process runs

[CryoThrust]

Fixes #2838.

LocalFilesystemWithShell.execute waited for the process before consuming stdout and stderr. Commands producing more than the OS pipe buffer could deadlock and be reported as timeouts.

This change starts daemon stream readers immediately after process startup, waits for the process with the existing timeout, and then collects both outputs. It preserves output truncation and timeout response behavior and adds a regression test covering approximately 108 KB of stdout.

Signed-off-by: Yohanes CryoThrust@users.noreply.github.com

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[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 10 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ent/filesystem/local/LocalFilesystemWithShell.java	60.00%	8 Missing and 2 partials ⚠️

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