[fix](fe) Prevent pushing other join conditions to right child of null-aware anti join when hash conjuncts are empty

fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/PushDownJoinOtherCondition.java

@@ -86,7 +86,16 @@ && allCoveredBy(otherConjunct, join.left().getOutputSet())) {
                             leftConjuncts.add(otherConjunct);
                         } else if (PUSH_DOWN_RIGHT_VALID_TYPE.contains(join.getJoinType())
                                 && allCoveredBy(otherConjunct, join.right().getOutputSet())) {
-                            rightConjuncts.add(otherConjunct);
+                            // For NULL_AWARE_LEFT_ANTI_JOIN (NOT IN subquery), when hash join
+                            // conjuncts are empty (no correlation), pushing other conditions to
+                            // the right child would filter rows before the null-aware check,
+                            // changing the NOT IN semantics. Keep them as remaining other
+                            // conjuncts instead.
+                            if (join.getJoinType().isNullAwareLeftAntiJoin() && join.getHashJoinConjuncts().isEmpty()) {
+                                remainingOther.add(otherConjunct);
+                            } else {
+                                rightConjuncts.add(otherConjunct);
+                            }
                         } else {
                             remainingOther.add(otherConjunct);
                         }

regression-test/data/query_p0/subquery/subquery_unnesting.out

@@ -1535,3 +1535,6 @@
 0
 2
 
+-- !select65 --
+0
+

regression-test/suites/query_p0/subquery/subquery_unnesting.groovy

@@ -140,4 +140,9 @@ suite ("subquery_unnesting") {
         from t1
         order by kk
         """
+    qt_select65 """
+        SELECT COUNT(*) AS c
+        FROM (SELECT 1 AS x) t
+        WHERE 1 NOT IN (SELECT CAST(NULL AS INT));
+    """
 }