tests/func: Add test case to test data integrity after changing my address of sheep process

If modifying the "my address" of sheep parameter without intention,
the cluster treates it as a new node so that we know the operation is wrong.
However, when trying to revert, we find out the prior created vdi is lost.

Signed-off-by: Ruoyu <liangry@ucweb.com>
Signed-off-by: Liu Yuan <namei.unix@gmail.com>