test: speedup wallet tests by whitelisting peers (immediate tx relay)

test/functional/wallet_listsinceblock.py

@@ -23,6 +23,8 @@ class ListSinceBlockTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 4
         self.setup_clean_chain = True
+        # whitelist peers to speed up tx relay / mempool sync
+        self.extra_args = [["-whitelist=noban@127.0.0.1"]] * self.num_nodes
 
     def skip_test_if_missing_module(self):
         self.skip_if_no_wallet()