Every 5 minutes fetch_endpoint_model_metadata() re-runs the full server-type
waterfall (LM Studio -> Ollama -> llama.cpp -> vLLM), spraying 404s at
endpoints the server never exposes (e.g. /api/v1/models and /api/tags on a
vllm backend).
Add _endpoint_probe_path_cache (base_url -> server type) so the first
successful probe's result is reused for the lifetime of the process.
Subsequent refreshes skip straight to the known-good path.
Fixes#29971.
(cherry picked from commit f3d7a8960a93e33683298e51c91c1b22a876d4da)
uzaylisak
c889941916