Existing import* RPCs are disabled for descriptor wallets, so only do
these tests for legacy wallets.
This is a backport of [[https://github.com/bitcoin/bitcoin/pull/18788 | core#18788]] [3/16]
https://github.com/bitcoin/bitcoin/pull/18788/commits/553dbf9af4dea96e6a3e79bba9607003342029bd