Revert "Fix closing sessions"

[xingyaoww]

Reverts #6114

This merged PR is causing issue with /download endpoint hence causing our CI to fail now.

e.g., This commit adds new testcases that relies on copy_from method that uses /download.

CI error: https://github.com/All-Hands-AI/OpenHands/actions/runs/12793391296/job/35666481217

I just locally reproduced this, it seems after reverting this PR, the test started to work. With this commits, the zip downloaded from runtime has a size of 0B.

Originally posted by @xingyaoww in #6114 (comment)

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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:009a492-nikolaik   --name openhands-app-009a492   docker.all-hands.dev/all-hands-ai/openhands:009a492