[Nightly] Remove gen_ranktable logic (#4941)

### What this PR does / why we need it?
Since the `llmdatadist` has sunset, the logic gen_ranktable should also
be removed

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

Signed-off-by: wangli <wangli858794774@gmail.com>

tests/e2e/nightly/multi_node/config/models/DeepSeek-R1-W8A8.yaml

@@ -17,8 +17,6 @@ disaggregated_prefill:
   enabled: true
   prefiller_host_index: [0, 1]
   decoder_host_index: [2]
-  ranktable_gen_path: "examples/disaggregated_prefill_v1/gen_ranktable.py"
-  ranktable_path: "/tmp/ranktable.json"
 
 deployment:
   -