LookupBlockIndex only acts on BlockManager.
This is a backport of [[https://github.com/bitcoin/bitcoin/pull/20749 | core#20749]] [2, 3 & 4/17]
https://github.com/bitcoin/bitcoin/pull/20749/commits/15d20f40e1321b24963b40c12958c7d30ad112ec
https://github.com/bitcoin/bitcoin/pull/20749/commits/eae54e6e60d7ed05b29d8345c0bb055397149ce8
https://github.com/bitcoin/bitcoin/pull/20749/commits/3664a150ac7547c9336b571557af223d9e31aac9