Fixes #23997 (review).
From Russ Yanofsky:
Agree with all of Marco’s points here and think this should be updated
If havePrune and hasAssumedValidChain are both true, better to show havePrune error message. Assumed-valid error message is vague and not very actionable. Would suggest “Error loading wallet. Wallet requires blocks to be downloaded, and software does not currently support loading wallets while blocks are being downloaded out of order though assumeutxo snapshots. Wallet should be able to load successfully after node sync reaches height {block_height}”