[wallet] Remove AddAccountingEntry()
Summary:
Function no longer used.
Partial backport of Core PR13825
https://github.com/bitcoin/bitcoin/pull/13825/commits/cf15ebd80c1f7b854c10240a979e661fe7a6d393
Depends on D5411
Test Plan:
ninja check
Reviewers: O1 Bitcoin ABC, #bitcoin_abc, jasonbcox
Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, jasonbcox
Differential Revision: https://reviews.bitcoinabc.org/D5413