<fix>[zwatch]: add hidden column to AlarmVO/EventSubscriptionVO

- move ZSTAC-83966 hidden-column migration out of V5.5.12__schema.sql
- add follow-up migration V5.5.12.1__schema.sql for AlarmVO/EventSubscriptionVO/ActiveAlarmVO hidden fields

Resolves: ZSTAC-83966

Change-Id: Ic660df81e306f8cb64348289604810c27dd63ae0

Author: chao.he

conf/db/upgrade/V5.5.12.1__schema.sql

@@ -0,0 +1,4 @@
+-- ZSTAC-83966: Add hidden field to AlarmVO/EventSubscriptionVO/ActiveAlarmVO for soft-hide support
+CALL ADD_COLUMN('AlarmVO', 'hidden', 'TINYINT(1)', 0, '0');
+CALL ADD_COLUMN('EventSubscriptionVO', 'hidden', 'TINYINT(1)', 0, '0');
+CALL ADD_COLUMN('ActiveAlarmVO', 'hidden', 'TINYINT(1)', 0, '0');