wallet: remove -salvagewallet
Summary:
Partial backport (3/11) of core PR18918:
https://github.com/bitcoin/bitcoin/pull/18918/commits/d321046f4bb4887742699c586755a21f3a2edbe1
Depends on D8589.
Test Plan:
ninja all check-functional
Reviewers: #bitcoin_abc, majcosta
Reviewed By: #bitcoin_abc, majcosta
Differential Revision: https://reviews.bitcoinabc.org/D8590