Fix bug for rolling update pd

common_tasks/get_pd_name.yml

@@ -9,6 +9,9 @@
   register: pd_info
 
 - set_fact:
-    pd_name: "{{ pd_info.json.members | json_query(query) }}"
+    pd_name_list: "{{ pd_info.json.members | json_query(query) }}"
   vars:
     query: '[?client_urls==[`http://{{ pd_addr }}`]].name'
+
+- set_fact:
+    pd_name: "{{ pd_name_list[0] }}"