We don't remove yet Chain locks as we need to preserve lock
order with CWallet one until swapping at once to avoid
deadlock failures (spotted by --enable-debug)
---
https://github.com/bitcoin/bitcoin/pull/15931/commits/b66c429c56c85fa16c309be0b2bca9c25fdd3e1a
Depends on D7512
Partial backport of PR15931