hotfix(frontend): Prevent too many re-renders

[amanape]

• [ ] This change is worth documenting at https://docs.all-hands.dev/
• [ ] Include this change in the Release Notes. If checked, you must provide an end-user friendly description for your change below

End-user friendly description of the problem this fixes or functionality this introduces. All of messages would re-render in user actions such as typing in input, or even scrolling!

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Summarize what the PR does, explaining any non-trivial design decisions. Only re-render if message lengths are different

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Link of any specific issues this addresses:

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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:014af46-nikolaik   --name openhands-app-014af46   docker.all-hands.dev/all-hands-ai/openhands:014af46

[openhands-staging[bot]]

Looks like there are a few issues preventing this PR from being merged!

• GitHub Actions are failing:
  • Run Python Unit Tests
  • Docker

If you'd like me to help, just leave a comment, like

@OpenHands please fix the failing actions on PR #8670

Feel free to include any additional details that might help me get this PR into a better state.

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