fix: Simplify nested f-string to fix pydoc-markdown parsing

[malhotra5]

This PR fixes the build docusaurus GitHub action failure by simplifying a nested f-string that was causing pydoc-markdown to fail parsing on main (https://github.com/All-Hands-AI/OpenHands/actions/runs/13318999934/job/37199704374).

This issue was introduced in #6458

Changes

• Split the complex nested f-string in gitlab.py into two separate lines
• Maintains the same functionality while making the code more readable
• Should resolve the documentation build error

Testing

• The code change is functionally equivalent
• Documentation build should now succeed

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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:5b9d790-nikolaik   --name openhands-app-5b9d790   docker.all-hands.dev/all-hands-ai/openhands:5b9d790

[enyst]

Let's try it, thank you!

For some reason I don't see that build in CI (it's optional on a PR, but I thought it will be listed 🤷).

Either way, let's merge, if it's broken.