We can't support a reset of the dbwrapper object when in-memory configuration is used
because it results in the permanent loss of coins. This only affects unittest
configurations (since that's the only place we use in-memory CCoinsViewDB instances).
This is a backport of core#19806 [3/8]
https://github.com/bitcoin/bitcoin/pull/19806/commits/ad949ba449ff2115e3d22c71f5b6509f11112098