fix(frontend): Refetch conversations when toggling the conversation panel

[amanape]

End-user friendly description of the problem this fixes or functionality that this introduces

• Include this change in the Release Notes. If checked, you must provide an end-user friendly description for your change below

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Give a summary of what the PR does, explaining any non-trivial design decisions

• staleTime is set to the default when fetching conversations
• Move query config to frontend/src/query-client-config.ts to use in tests without hydration errors

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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:15aabc4-nikolaik   --name openhands-app-15aabc4   docker.all-hands.dev/all-hands-ai/openhands:15aabc4

[rbren]

does this mean we refetch constantly? Should it be something like 5s?

[amanape]

No:

Stale queries are refetched automatically in the background when:

• New instances of the query mount
• The window is refocused
• The network is reconnected
• The query is optionally configured with a refetch interval

source: https://tanstack.com/query/latest/docs/framework/react/guides/important-defaults

Really it just means that we will refetch every time the panel is toggled since the data is always stale. staleTime: 0 is actually the TanStack Query default, that is why we previously fetched frequently