Here we go again.
First my disclaimers.
1) The Chazon Ish zt”l was a tzadik, Gaon, and Kadosh – not that he needs my haskama.
2) People of the very rare caliber of the Chazon Ish are quite possibly endowed with kochos and siyata dishmaya, that is beyond normal.
Having said that.
1) That fact that the story has been told does not create a chiyuv to believe it. It is a personal choice.
2) It is at least as likely to be untrue as it is to be true. (There are some serious problems with the story, at least in the version told above.)
3) One’s choice to believe it or not believe it reflects more on their personality than on their level of emunah.