[backport#17300] LegacyScriptPubKeyMan code cleanups
Summary:
Fix missing strFailReason in CreateTransaction (Russell Yanofsky) Fix misplaced AssertLockHeld (Russell Yanofsky) doc: Clarify WalletStorage / Wallet relation (Russell Yanofsky) Add back mistakenly removed AssertLockHeld (Russell Yanofsky) Refactor: Add GetLegacyScriptPubKeyMan helper (Russell Yanofsky)
Pull request description:
This PR implements suggested code cleanups from https://github.com/bitcoin/bitcoin/pull/17260 review comments
https://github.com/bitcoin/bitcoin/pull/17300/files
Depends on D7119
Backport of Core PR17300
Test Plan:
ninja check check-functional
Reviewers: #bitcoin_abc, jasonbcox
Reviewed By: #bitcoin_abc, jasonbcox
Differential Revision: https://reviews.bitcoinabc.org/D7128