This changes -wallet setting to only load existing wallets, not create new ones.
- Fixes settings.json corner cases reported by sjors & promag:
https://github.com/bitcoin-core/gui/issues/95,
https://github.com/bitcoin/bitcoin/pull/19754#issuecomment-685858578,
https://github.com/bitcoin/bitcoin/pull/19754#issuecomment-685858578
- Prevents accidental creation of wallets reported most recently by jb55
http://www.erisian.com.au/bitcoin-core-dev/log-2020-09-14.html#l-355
- Simplifies behavior after #15454. #15454 took the big step of disabling
creation of the default wallet. This PR extends it to avoid creating other
wallets as well. With this change, new wallets just aren't created on
startup, instead of sometimes being created, sometimes not. #15454 release
notes are updated here and are simpler.
It is a bug fix and simplifies behavior of the core#15937 / core#19754 / core#15454 features
This is a backport of core#20186
Depends on D15143 and D14142