Bump the wallet version number to 190700 so that new wallets made without a default key will no longer work on previous versions at all. Also remove the usehd option to avoid weird interaction with wallet version numbers and HD-ness of wallets.
Backport of core PR11250 and PR11285
https://github.com/bitcoin/bitcoin/pull/11250/files
https://github.com/bitcoin/bitcoin/pull/11285/files