ai_run_benchmarks: minor lint fix

We have this on ansible warnings:

task 24: debian13-ai debian13-ai-dev[WARNING]: Encountered 1 template error.
error 1 - 'item' is undefined
Origin: /data/minio/kdevops/playbooks/roles/ai_run_benchmarks/tasks/main.yml:155:13

153         timeout: 300
154
155     - name: Run Milvus benchmark for iteration {{ item }}
                ^ column 13

task 25. [started TASK: ai_run_benchmarks : Run Milvus benchmark for iteration << error 1 - 'item' is undefined >> on debian13-ai]
 [started TASK: ai_run_benchmarks : Run Milvus benchmark for iteration << error 1 - 'item' is undefined >> on debian13-ai-dev]

The warning message is Ansible's way of showing that it couldn't evaluate
the template expression in the task name. This happens because:
  - Task names are evaluated before the loop starts
  - The item variable only exists during each loop iteration
  - So when Ansible tries to display the task name at the start, item doesn't exist yet

Fix this.

Generated-by: Claude AI
Signed-off-by: Luis Chamberlain <[email protected]>

Author: mcgrof

playbooks/roles/ai_run_benchmarks/tasks/main.yml

@@ -152,7 +152,7 @@
         delay: 10
         timeout: 300
 
-    - name: Run Milvus benchmark for iteration {{ item }}
+    - name: Run Milvus benchmark iterations
       ansible.builtin.command: >
         {{ ai_benchmark_results_dir }}/venv/bin/python
         {{ ai_benchmark_results_dir }}/workdir/milvus_benchmark.py