[fix](memory) Fix bthread_setspecific log fatal on UBSAN build (#18274)

be/src/runtime/thread_context.h

@@ -191,6 +191,11 @@ private:
     TUniqueId _fragment_instance_id;
 };
 
+#if defined(UNDEFINED_BEHAVIOR_SANITIZER)
+static ThreadContext* thread_context() {
+    return thread_context_ptr._ptr;
+}
+#else
 // Cache the pointer of bthread local in pthead local,
 // Avoid calling bthread_getspecific frequently to get bthread local, which has performance problems.
 static void pthread_attach_bthread() {
@@ -225,6 +230,7 @@ static ThreadContext* thread_context() {
         return thread_context_ptr._ptr;
     }
 }
+#endif
 
 class ScopeMemCount {
 public: