Add disagg test to v6e-8 queue (#1259)

Author: sixiang-google

.buildkite/features/Single-Host-P-D-disaggregation.yml

@@ -5,7 +5,7 @@ steps:
     key: "SingleHostPDDisaggregation_CorrectnessTest"
     soft_fail: true
     agents:
-      queue: tpu_v6e_queue
+      queue: tpu_v6e_8_queue
     commands:
       - |
         .buildkite/scripts/run_in_docker.sh \