[ci] Check what happens when building with tbb=ON

As described in #19798, we have an old build option that was supposedly
removed, but it is still considered in the implementation of
`ROOT::gCoreMutex`.

It would be good to know what happens when testing ROOT with it (no
differences are expected from the performance optimization with TBB, and
actually it was always enabled when building with `builtin_tbb=ON` as
well, as we do for macOS and Windows).

Author: guitargeek

.github/workflows/root-ci-config/buildconfig/global.txt

@@ -10,6 +10,7 @@ mathmore=ON
 minuit2_omp=ON
 roofit_multiprocess=ON
 roottest=ON
+tbb=ON
 test_distrdf_dask=ON
 test_distrdf_pyspark=ON
 testing=ON