### What this PR does / why we need it?
fix a typo in mooncake layerwise connector. There is only `requests`,
instead of `request` in `connector_metadata`. This pr fixes this typo
- vLLM version: v0.11.0rc3
- vLLM main:
83f478bb19
Signed-off-by: liziyu <liziyu16@huawei.com>