[CP] fix check ls gc in standby when the tenant switchover to primary and its ls list not match with the original

src/share/ob_debug_sync_point.h

@@ -560,6 +560,7 @@ class ObString;
     ACT(BEFORE_PROCESS_EVENT_TASK,)\
     ACT(BEFORE_CHECK_LS_TRANSFER_SCN_FOR_STANDBY,)\
     ACT(BEFORE_GET_CONFIG_VERSION_AND_TRANSFER_SCN,)\
+    ACT(LS_GC_BEFORE_OFFLINE,)\
     ACT(MAX_DEBUG_SYNC_POINT,)
 
 DECLARE_ENUM(ObDebugSyncPoint, debug_sync_point, OB_DEBUG_SYNC_POINT_DEF);