Fix test_system_merges after optimization for "x OR 1" conditions

After the previous patch "x OR 1" will not execute "x", and because of
this test_system_merges::test_mutation_simple started to fail since
"sleep" function did not executed.

Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>

tests/integration/test_system_merges/test.py

@@ -188,7 +188,7 @@ def test_mutation_simple(started_cluster, replicated):
         # ALTER will sleep for 9s
         def alter():
             node1.query(
-                f"ALTER TABLE {name} UPDATE a = 42 WHERE sleep(9) OR 1",
+                f"ALTER TABLE {name} UPDATE a = 42 WHERE sleep(9) = 0",
                 settings=settings,
             )