perf tests switch-tracking: Set this test to run exclusively

perf tests switch-tracking: Set this test to run exclusively

This test was failing when run with the default 'perf test' mode, which
is to run multiple regression tests in parallel.

Since it checks system_wide mode, set it to run in exclusive mode.

Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/lkml/Z1yPYqYYs_isO1PJ@x1
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>