[skip e2e]Update etcd follower num to apply chaos (#27083)

Signed-off-by: zhuwenxing <wenxing.zhu@zilliz.com>

tests/python_client/chaos/test_chaos_apply_to_determined_pod.py

@@ -82,6 +82,9 @@ class TestChaosApply:
             if etcd_followers is None:
                 raise Exception("no etcd followers")
             target_pod_list.extend(etcd_followers)
+            if len(target_pod_list) >=2:
+                # only choose one follower to apply chaos
+                target_pod_list = target_pod_list[0]
         log.info(f"target_pod_list: {target_pod_list}")
         chaos_type = chaos_type.replace('_', '-')
         chaos_config = cc.gen_experiment_config(f"{str(Path(__file__).absolute().parent)}/chaos_objects/template/{chaos_type}-by-pod-list.yaml")