fix: IF NOT EXISTS 절 제거 (#139)

Author: move-hoon

infra/src/main/resources/db/migration/mysql/V20251116_001__add_deleted_at_to_device_notification.sql

@@ -1,5 +1,5 @@
 ALTER TABLE device
-ADD COLUMN IF NOT EXISTS deleted_at DATETIME(6) NULL COMMENT '삭제 시간';
+ADD COLUMN deleted_at DATETIME(6) NULL COMMENT '삭제 시간';
 
 ALTER TABLE notification
-ADD COLUMN IF NOT EXISTS deleted_at DATETIME(6) NULL COMMENT '삭제 시간';
+ADD COLUMN deleted_at DATETIME(6) NULL COMMENT '삭제 시간';