Update gitlab integration docs

[mamoodi]

• 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.

Update gitlab integration docs

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Summarize what the PR does, explaining any non-trivial design decisions.

I wasn't able to get gitlab resolver working. Once that is working, we should update the docs on how it works just like the github docs.

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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:3d68dc7-nikolaik   --name openhands-app-3d68dc7   docker.all-hands.dev/all-hands-ai/openhands:3d68dc7

[mamoodi]

The docs for this are now embedded inside the github integration.
When gitlab works, we will do the same for that.

[openhands-ai]

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 #8946

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

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