End-user friendly description of the problem this fixes or functionality that this introduces

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Give a summary of what the PR does, explaining any non-trivial design decisions

I still haven't tracked down the source of the memory leak, but the repro is something like:

• upload a ~10MB text file to the workspace
• ask openhands to run cat bigfile.txt
• repeatedly refresh the page

You'll see mem usage jump by ~12MB on each refresh.

This seems to cut down on most of the leakage, but there's probably a separate leak somewhere

Link of any specific issues this addresses

To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:9cab1e9-nikolaik   --name openhands-app-9cab1e9   docker.all-hands.dev/all-hands-ai/openhands:9cab1e9