rpc: Include assumeutxo as a failure reason of rescanblockchain
Summary:
This concludes backport of core#30909
https://github.com/bitcoin/bitcoin/pull/30909/commits/42d5d5336319aaf0f07345037db78239d9e012fc
https://github.com/bitcoin/bitcoin/pull/30909/commits/9d2d9f7ce29636f08322df70cf6abec8e0ca3727
Depends on D17931
Test Plan: ninja all check-all
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D17948