test: create assert_not_equal util and add to where imports are needed

In the functional tests there are lots of cases where we assert != which
this new util will replace, we also are adding the imports and the new assertion

test/functional/test_framework/p2p.py

@@ -77,6 +77,7 @@ from test_framework.messages import (
     sha256,
 )
 from test_framework.util import (
+    assert_not_equal,
     MAX_NODES,
     p2p_port,
     wait_until_helper_internal,
@@ -897,7 +898,7 @@ class P2PDataStore(P2PInterface):
             if success:
                 self.wait_until(lambda: node.getbestblockhash() == blocks[-1].hash, timeout=timeout)
             else:
-                assert node.getbestblockhash() != blocks[-1].hash
+                assert_not_equal(node.getbestblockhash(), blocks[-1].hash)
 
     def send_txs_and_test(self, txs, node, *, success=True, expect_disconnect=False, reject_reason=None):
         """Send txs to test node and test whether they're accepted to the mempool.