[CI/UT] Fix disaggregated prefill ci (#1313)

### What this PR does / why we need it?
Use eager mode to run disaggregated prefill ci

### Does this PR introduce _any_ user-facing change?
N/A

### How was this patch tested?
CI passed with new existing test.

---------

Signed-off-by: MengqingCao <cmq0113@163.com>

tests/e2e/pd_disaggreate/setup_pd.sh

@@ -66,6 +66,7 @@ function run_prefill_instance() {
   --served-model-name Deepseek \
   --max-model-len 2000 \
   --trust-remote-code \
+  --enforce-eager \
   --kv-transfer-config "$KV_CONFIG"
 }
 
@@ -119,6 +120,7 @@ function run_decode_instance() {
     --max-num-batched-tokens 2000 \
     --trust-remote-code \
     --gpu-memory-utilization 0.9 \
+    --enforce-eager \
     --kv-transfer-config "$KV_CONFIG"
 }