test: Speed up wallet_resendwallettransactions test with mockscheduler RPC
Summary:
Before:
wallet_resendwallettransactions.py | ✓ Passed | 14 s wallet_resendwallettransactions.py | ✓ Passed | 7 s wallet_resendwallettransactions.py | ✓ Passed | 9 s
After
wallet_resendwallettransactions.py | ✓ Passed | 3 s wallet_resendwallettransactions.py | ✓ Passed | 4 s wallet_resendwallettransactions.py | ✓ Passed | 6 s
Also fixes core#20143
This is a backport of core#20112
Test Plan: ninja check-functional
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D9999