Fix resendwallettransactions assert failure if -walletbroadcast=0

Summary: Backport core's PR11002 and PR10995

Test Plan:

make check
Run the resendwallettransactions test

Reviewers: #bitcoin_abc, matiu, schancel

Reviewed By: #bitcoin_abc, matiu, schancel

Subscribers: teamcity

Differential Revision: https://reviews.bitcoinabc.org/D1059