[SPARK-3170][CORE][BUG]:RDD info loss in "StorageTab" and "ExecutorTab"

compeleted stage only need to remove its own partitions that are no longer cached. However, "StorageTab" may lost some rdds which are cached actually. Not only in "StorageTab", "ExectutorTab" may also lose some rdd info which have been overwritten by last rdd in a same task.
1. "StorageTab": when multiple stages run simultaneously, completed stage will remove rdd info which belong to other stages that are still running.
2. "ExectutorTab": taskcontext may lose some "updatedBlocks" info of  rdds  in a dependency chain. Like the following example:
         val r1 = sc.paralize(..).cache()
         val r2 = r1.map(...).cache()
         val n = r2.count()

When count the r2, r1 and r2 will be cached finally. So in CacheManager.getOrCompute, the taskcontext should contain "updatedBlocks" of r1 and r2. Currently, the "updatedBlocks" only contain the info of r2. 
I raised this in the other PR and since we have a new one I'll just ask again. Can you explain what this fixes? My understanding is that this can only be called once per task, and since this is the only place where we set `updatedBlocks` I don't see how the original `TaskMetrics` could already have updated blocks.