EVM: adapt failing test

The following discussion from !14186 (merged) should be addressed:

• @vch9 started a discussion: (+2 comments)

  Probably intereesting to track this via an issue.

  Basically reverting a kernel is no longer possible with the new migration behavior. In this this, the kernel has version 13, and when we perform migration on the ghostnet kernel with version 12, it fails to read the kernel version from the storage as 13 is not part of the enum.

  This test has nothing to do with reverting to a previous kernel so we could change it to just prove it upgrades or not.

  But the main question is: do we want to accept reverting to previous storage versions? My feeling is yes we do