Migrate to modern TBB version (#6300)

unit_tests/partitioner/recursive_bisection.cpp

@@ -7,15 +7,6 @@
 
 #include <boost/test/unit_test.hpp>
 
-// make sure not to leak in recursive bisection
-#if TBB_VERSION_MAJOR == 2020
-#include <tbb/global_control.h>
-tbb::global_control scheduler(tbb::global_control::max_allowed_parallelism, 2);
-#else
-#include <tbb/task_scheduler_init.h>
-tbb::task_scheduler_init init(2);
-#endif
-
 using namespace osrm::partitioner;
 using namespace osrm::util;