[refactor](taskqueue) remove old task scheduler based wg (#30832)

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Co-authored-by: yiguolei <yiguolei@gmail.com>

be/src/runtime/query_context.cpp

@@ -162,9 +162,7 @@ void QueryContext::set_query_scheduler(uint64_t tg_id) {
 
 doris::pipeline::TaskScheduler* QueryContext::get_pipe_exec_scheduler() {
     if (_task_group) {
-        if (!config::enable_cgroup_cpu_soft_limit) {
-            return _exec_env->pipeline_task_group_scheduler();
-        } else if (_task_scheduler) {
+        if (_task_scheduler) {
             return _task_scheduler;
         }
     }