[SPARK-3941][CORE] _remainingmem should not increase twice when updateBlockInfo

In BlockManagermasterActor, _remainingMem would increase memSize for twice when updateBlockInfo if new storageLevel is invalid and old storageLevel is "useMemory". Also, _remainingMem should increase with original memory size instead of new memSize.
I see, we want to release the `originalMemSize` and occupy the new `memSize`. That makes sense. It seems that the old code is just wrong then.