<fix>[shared_block]: return none if no pv strategy.
<fix>[shared_block]: return none if no pv strategy.

list.remove(item) will raise ValueError if item not in list.

Resolves: ZSTAC-44535

Change-Id: I66666a75626b787762616d7669677569786c7669

zstackio/zstack-utility,zstackio/zstack-utility,zstackio/zstack-utility