test: Update EXPLAIN expected to include null_aware suffix

Upstream #22913 added the `null_aware` status to Join node display.
The correlated multi-column NOT IN case was already producing a
null-aware LeftAnti join (verified: it returns standard-SQL three-valued
results — empty correlated subquery keeps the row, NULL-bearing subquery
excludes it); only the EXPLAIN output now surfaces the flag. Update the
expected logical and physical plans accordingly.

Co-authored-by: Claude Code

Author: viirya

datafusion/sqllogictest/test_files/null_aware_anti_join.slt

@@ -536,15 +536,15 @@ WHERE (c2, c3) NOT IN (
 );
 ----
 logical_plan
-01)LeftAnti Join: t1.c2 = __correlated_sq_1.c2, t1.c3 = __correlated_sq_1.c3, t1.c1 = __correlated_sq_1.c1
+01)LeftAnti Join: t1.c2 = __correlated_sq_1.c2, t1.c3 = __correlated_sq_1.c3, t1.c1 = __correlated_sq_1.c1 null_aware
 02)--SubqueryAlias: t1
 03)----TableScan: test_multi projection=[c1, c2, c3]
 04)--SubqueryAlias: __correlated_sq_1
 05)----Projection: t2.c2, t2.c3, t2.c1
 06)------SubqueryAlias: t2
 07)--------TableScan: test_multi projection=[c1, c2, c3]
 physical_plan
-01)HashJoinExec: mode=CollectLeft, join_type=LeftAnti, on=[(c2@1, c2@0), (c3@2, c3@1), (c1@0, c1@2)]
+01)HashJoinExec: mode=CollectLeft, join_type=LeftAnti, on=[(c2@1, c2@0), (c3@2, c3@1), (c1@0, c1@2)], null_aware
 02)--DataSourceExec: partitions=1, partition_sizes=[1]
 03)--DataSourceExec: partitions=1, partition_sizes=[1]