### What this PR does / why we need it? Disables `FULL_DECODE_ONLY` end-to-end test that fails intermittently. This prevents CI blockages while the root cause of the flakiness is investigated. ### Does this PR introduce _any_ user-facing change? None. ### How was this patch tested? None needed. - vLLM version: v0.11.0rc3 - vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0 Signed-off-by: Yizhou Liu <liu_yizhou@outlook.com>