test: makes timeout a forced named argument in tests methods that use it

This makes calls to such methods more explicit and less error prone

test/functional/feature_assumevalid.py

@@ -159,7 +159,7 @@ class AssumeValidTest(BitcoinTestFramework):
         for i in range(2202):
             p2p1.send_message(msg_block(self.blocks[i]))
         # Syncing 2200 blocks can take a while on slow systems. Give it plenty of time to sync.
-        p2p1.sync_with_ping(960)
+        p2p1.sync_with_ping(timeout=960)
         assert_equal(self.nodes[1].getblock(self.nodes[1].getbestblockhash())['height'], 2202)
 
         p2p2 = self.nodes[2].add_p2p_connection(BaseNode())