In the next commit, we start using BlockConnected/BlockDisconnected
callbacks to establish tx depth, rather than querying the chain
directly.
Currently, BlockUntilSyncedToCurrentChain will return early if
the best block processed by the wallet is a descendant of the node'tip.
That means that in the case of a re-org, it won't wait for the
BlockDisconnected callbacks that have been enqueued during the re-org
but have not yet been triggered in the wallet.
Change BlockUntilSyncedToCurrentChain to only return early if the
wallet's m_last_block_processed matches the tip exactly. This ensures
that there are no BlockDisconnected or BlockConnected callbacks
in-flight.
https://github.com/bitcoin/bitcoin/pull/15931/commits/f77b1de16feee097a88e99d2ecdd4d84beb4f915
Depends on D7510
Partial backport of Core PR15931