test: address review — fix additional IS lock sync sites and remove dead code

Add sync_mempools() to two more tests with the same vulnerable pattern:
- feature_llmq_is_cl_conflicts.py: no whitelist, waits on all nodes
- interface_zmq_dash.py: three locations (low risk due to whitelist,
  but fixed for consistency)

Remove dead wait_for_tx() method from feature_llmq_is_retroactive.py
whose call sites were all replaced with sync_mempools in the prior commit.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: UdjinM6

test/functional/feature_llmq_is_cl_conflicts.py

@@ -244,6 +244,7 @@ def test_chainlock_overrides_islock_overrides_nonchainlock(self):
         self.nodes[0].sendrawtransaction(rawtx2)
         # bump mocktime to force tx relay
         self.bump_mocktime(60)
+        self.sync_mempools()
         for node in self.nodes:
             self.wait_for_instantlock(rawtx2_txid, node)
 

test/functional/feature_llmq_is_retroactive.py

@@ -35,16 +35,6 @@ def sleep_and_assert_no_instantlock(self, txid, node, sleep=5):
         time.sleep(sleep)
         self.assert_no_instantlock(txid, node)
 
-    # random delay before tx is actually send by network could take up to 30 seconds
-    def wait_for_tx(self, txid, node, expected=True, timeout=60):
-        def check_tx():
-            try:
-                return node.getrawtransaction(txid)
-            except Exception:
-                return False
-        if self.wait_until(check_tx, timeout=timeout, do_assert=expected) and not expected:
-            raise AssertionError("waiting unexpectedly succeeded")
-
     def create_fund_sign_tx(self):
         rawtx = self.nodes[0].createrawtransaction([], {self.nodes[0].getnewaddress(): 1})
         rawtx = self.nodes[0].fundrawtransaction(rawtx)['hex']

test/functional/interface_zmq_dash.py

@@ -297,6 +297,7 @@ def test_instantsend_publishers(self):
         # Send the first transaction and wait for the InstantLock
         rpc_raw_tx_1_hash = self.nodes[0].sendrawtransaction(rpc_raw_tx_1['hex'])
         self.bump_mocktime(30)
+        self.sync_mempools()
         self.wait_for_instantlock(rpc_raw_tx_1_hash, self.nodes[0])
         # Validate hashtxlock
         zmq_tx_lock_hash = self.subscribers[ZMQPublisher.hash_tx_lock].receive().read(32).hex()
@@ -350,6 +351,7 @@ def test_instantsend_publishers(self):
         # Now send the tx itself
         self.test_node.send_tx(from_hex(msg_tx(),rpc_raw_tx_3['hex']))
         self.bump_mocktime(30)
+        self.sync_mempools()
         self.wait_for_instantlock(rpc_raw_tx_3['txid'], self.nodes[0])
         # Validate hashtxlock
         zmq_tx_lock_hash = self.subscribers[ZMQPublisher.hash_tx_lock].receive().read(32).hex()
@@ -384,6 +386,7 @@ def test_governance_publishers(self):
         proposal_hex = ''.join(format(x, '02x') for x in json.dumps(proposal_data).encode())
         collateral = self.nodes[0].gobject("prepare", "0", proposal_rev, proposal_time, proposal_hex)
         self.bump_mocktime(30)
+        self.sync_mempools()
         self.wait_for_instantlock(collateral, self.nodes[0])
         self.generate(self.nodes[0], 6, sync_fun=lambda: self.sync_blocks())
         rpc_proposal_hash = self.nodes[0].gobject("submit", "0", proposal_rev, proposal_time, proposal_hex, collateral)