test: speedup wallet_listtransactions by whitelisting peers (immediate tx relay)

Summary:
By whitelisting the peers via -whitelist, the inventory is transmitted immediately rather than on average every 5 seconds, speeding up the test by at least a factor of two:

Before:

wallet_listtransactions.py               | ✓ Passed  | 7 s
wallet_listtransactions.py --descriptors | ✓ Passed  | 18 s

After:

wallet_listtransactions.py               | ✓ Passed  | 4 s
wallet_listtransactions.py --descriptors | ✓ Passed  | 5 s

This is a commit from core#22423
https://github.com/bitcoin/bitcoin/pull/22423/commits/fb6c6a7938cb7c4808ad88d23bfc2b7408407b12

Test Plan: ninja check-functional

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10858