Recompute density and enthalpy instead of reconstructing #7924

Job	Run time
Build SU2 (BaseMPI)	13m 18s
Build SU2 (ReverseMPI)	13m 55s
Build SU2 (ForwardMPI)	11m 9s
Build SU2 (BaseNoMPI)	7m 36s
Build SU2 (ReverseNoMPI)	12m 22s
Build SU2 (ForwardNoMPI)	10m 9s
Build SU2 (BaseOMP)	7m 32s
Build SU2 (ReverseOMP)	15m 40s
Build SU2 (ForwardOMP)	10m 31s
Build SU2 (asan) (BaseNoMPI-asan)	15m 49s
Build SU2 (asan) (ReverseNoMPI-asan)	43m 56s
Build SU2 (tsan) (BaseOMP-tsan)	12m 6s
Build SU2 (tsan) (ReverseOMP-tsan)	27m 1s
Unit Tests (test_driver)	51s
Regression Tests (vandv.py)	2m 11s
Unit Tests (test_driver_AD)	1m 30s
Regression Tests (tutorials.py)	4m 41s
Unit Tests (test_driver_DD)	50s
Regression Tests (parallel_regression.py)	2m 3s
Regression Tests (parallel_regression_AD.py)	9m 37s
Regression Tests (serial_regression.py)	15m 36s
Regression Tests (serial_regression_AD.py)	5m 11s
Regression Tests (hybrid_regression.py)	10m 58s
Regression Tests (hybrid_regression_AD.py)	3m 26s
Thread Sanitizer Tests (hybrid_regression.py)	27m 31s
Thread Sanitizer Tests (hybrid_regression_AD.py)	8m 51s
Address Sanitizer Tests (serial_regression.py)	15m 18s
Address Sanitizer Tests (serial_regression_AD.py)	5m 40s
	5h 15m 18s

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