[Chore](result-sink) set ENABLE_PARALLEL_RESULT_SINK default value to true

fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java

@@ -1324,7 +1324,7 @@ public enum IgnoreSplitType {
     public long runtimeFilterMaxBuildRowCount = 64L * 1024L * 1024L;
 
     @VariableMgr.VarAttr(name = ENABLE_PARALLEL_RESULT_SINK, needForward = true, fuzzy = true)
-    private boolean enableParallelResultSink = false;
+    private boolean enableParallelResultSink = true;
 
     @VariableMgr.VarAttr(name = "sort_phase_num", fuzzy = true, needForward = true,
             description = {"如设置为1，则只生成1阶段sort，设置为2，则只生成2阶段sort，设置其它值，优化器根据代价选择sort类型",
@@ -3876,6 +3876,10 @@ public void setDisableNereidsRules(String disableNereidsRules) {
         this.disableNereidsRules = disableNereidsRules;
     }
 
+    public void setEnableParallelResultSink(boolean enableParallelResultSink) {
+        this.enableParallelResultSink = enableParallelResultSink;
+    }
+
     public void setDisableNereidsExpressionRules(String disableNereidsExpressionRules) {
         BitSet bitSet = new BitSet();
         for (String ruleName : disableNereidsExpressionRules.split(",")) {

fe/fe-core/src/test/java/org/apache/doris/nereids/rules/rewrite/SplitMultiDistinctTest.java

@@ -35,6 +35,7 @@ protected void runBeforeAll() throws Exception {
                 + "distributed by hash(a) properties('replication_num'='1');");
         connectContext.setDatabase("test");
         connectContext.getSessionVariable().setDisableNereidsRules("PRUNE_EMPTY_PARTITION");
+        connectContext.getSessionVariable().setEnableParallelResultSink(false);
     }
 
     @Test

regression-test/suites/nereids_p0/runtime_filter/cte-runtime-filter.groovy

@@ -16,7 +16,7 @@
 // under the License.
 
 suite('cte-runtime-filter') {
-
+    sql 'set enable_parallel_result_sink=false;'
     sql '''
     drop table if exists cte_runtime_filter_table;
     CREATE TABLE `cte_runtime_filter_table` (

regression-test/suites/nereids_rules_p0/adjust_nullable/test_subquery_nullable.groovy

@@ -16,6 +16,7 @@
 // under the License.
 
 suite('test_subquery_nullable') {
+    sql 'set enable_parallel_result_sink=false;'
     sql 'DROP TABLE IF EXISTS test_subquery_nullable_t1 FORCE'
     sql 'DROP TABLE IF EXISTS test_subquery_nullable_t2 FORCE'
     sql "CREATE TABLE test_subquery_nullable_t1(a int not null, b int not null, c int not null) distributed by hash(a) properties('replication_num' = '1')"

regression-test/suites/shape_check/others/nlj.groovy

@@ -18,6 +18,7 @@
  */
 
 suite("nlj") {
+    sql 'set enable_parallel_result_sink=false;'
     sql """
     drop table if exists a;
     create table a (