Fix cpu arch returned value in TestCase.py #7012

Job	Run time
Build SU2 (tsan) (BaseOMP-tsan)	13m 13s
Build SU2 (BaseMPI)	13m 58s
Build SU2 (tsan) (ReverseOMP-tsan)	30m 1s
Build SU2 (ReverseMPI)	14m 7s
Build SU2 (ForwardMPI)	12m 2s
Build SU2 (BaseNoMPI)	8m 30s
Build SU2 (ReverseNoMPI)	12m 37s
Build SU2 (ForwardNoMPI)	10m 29s
Build SU2 (BaseOMP)	8m 11s
Build SU2 (ReverseOMP)	15m 5s
Build SU2 (ForwardOMP)	10m 32s
Unit Tests (test_driver)	1m 14s
Regression Tests (vandv.py)	3m 16s
Unit Tests (test_driver_AD)	1m 13s
Regression Tests (tutorials.py)	5m 26s
Unit Tests (test_driver_DD)	1m 2s
Regression Tests (parallel_regression.py)	13m 40s
Regression Tests (parallel_regression_AD.py)	7m 24s
Regression Tests (serial_regression.py)	15m 35s
Regression Tests (serial_regression_AD.py)	5m 29s
Regression Tests (hybrid_regression.py)	10m 38s
Regression Tests (hybrid_regression_AD.py)	4m 27s
Thread Sanitizer Tests (hybrid_regression.py)	25m 53s
Thread Sanitizer Tests (hybrid_regression_AD.py)	10m 27s
	4h 14m 29s

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