Migrate to modern TBB version (#6300)

unit_tests/contractor/graph_contractor.cpp

@@ -4,13 +4,7 @@
 #include "helper.hpp"
 
 #include <boost/test/unit_test.hpp>
-
-#include <tbb/tbb_stddef.h> // For version lookup
-#if TBB_VERSION_MAJOR == 2020
 #include <tbb/global_control.h>
-#else
-#include <tbb/task_scheduler_init.h>
-#endif
 
 using namespace osrm;
 using namespace osrm::contractor;
@@ -20,11 +14,7 @@ BOOST_AUTO_TEST_SUITE(graph_contractor)
 
 BOOST_AUTO_TEST_CASE(contract_graph)
 {
-#if TBB_VERSION_MAJOR == 2020
     tbb::global_control scheduler(tbb::global_control::max_allowed_parallelism, 1);
-#else
-    tbb::task_scheduler_init scheduler(1);
-#endif
     /*
      *                 <--1--<
      * (0) >--3--> (1) >--3--> (3)