fix backup macro block reader not reset when in inner retry process

src/share/ob_debug_sync_point.h

@@ -420,6 +420,7 @@ class ObString;
     ACT(BEFORE_MIG_DDL_TABLE_MERGE_TASK,)\
     ACT(BEFORE_COPY_DDL_SSTABLE,)\
     ACT(BEFORE_DDL_WRITE_PREPARE_LOG,)\
+    ACT(AFTER_BACKUP_FETCH_MACRO_BLOCK_FAILED,)\
     ACT(MAX_DEBUG_SYNC_POINT,)
 
 DECLARE_ENUM(ObDebugSyncPoint, debug_sync_point, OB_DEBUG_SYNC_POINT_DEF);