fix 404 issue for /config

[rbren]

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no changelog

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We currently get a 404 when using local runtimes--this should fix that

I also changed the name of the API endpoint

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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:17e7cd6-nikolaik   --name openhands-app-17e7cd6   docker.all-hands.dev/all-hands-ai/openhands:17e7cd6