when use stormservice to deploy sglang pd case, "routing role" and "pd_disaggregation.go doPrefillRequest" which one make sense？？

### 🐛 Describe the bug

i want to deploy sglang pd, i use stormservice to make it.
1\ i found in stormservice there is a role named "routing", it seems the routing pod handle PD routing.
2\ but , i found in pkg/plugins/gateway/algorithms/pd_disaggregation.go there are two functions call, doPrefillRequest and preparePrefillPayload , those function call have already adapted SGLangEngine logic,

i don't know which one make sense

### Steps to Reproduce

none

### Expected behavior

none

### Environment

none

Start by reading pkg/plugins/gateway/algorithms/pd_disaggregation.go, especially doPrefillRequest and preparePrefillPayload, then trace the stormservice routing role mentioned in the issue. Compare the two request paths for an SGLang PD deployment; done means the responsible path and relationship between them are clearly established, with a reproducible deployment scenario if a code change is needed.

Written by the indexing model from the issue text.