Drop confusing kernel options:
BlockManagerOpts::reindex ChainstateLoadOptions::reindex ChainstateLoadOptions::reindex_chainstate
Replacing them with more straightforward options:
ChainstateLoadOptions::wipe_block_tree_db ChainstateLoadOptions::wipe_chainstate_db
Having two options called "reindex" which did slightly different things
was needlessly confusing (one option wiped the block tree database, and
the other caused block files to be rescanned). Also the previous set of
options did not allow rebuilding the block database without also
rebuilding the chainstate database, when it should be possible to do
those independently.
This is a partial backport of core#30132
https://github.com/bitcoin/bitcoin/pull/30132/changes/804f09dfa116300914e2aeef05ed9710dd504e8c
Depends on D20601