[WIP] fix multigrid agglomeration #8182

Job	Run time
Build SU2 (tsan) (BaseOMP-tsan)	11m 31s
Build SU2 (tsan) (ReverseOMP-tsan)	27m 27s
Build SU2 (asan) (BaseNoMPI-asan)	7m 29s
Build SU2 (BaseMPI)	12m 52s
Build SU2 (asan) (ReverseNoMPI-asan)	10m 20s
Build SU2 (ReverseMPI)	4m 46s
Build SU2 (ForwardMPI)	4m 22s
Build SU2 (BaseNoMPI)	3m 18s
Build SU2 (ReverseNoMPI)	4m 30s
Build SU2 (ForwardNoMPI)	3m 51s
Build SU2 (BaseOMP)	3m 11s
Build SU2 (ReverseOMP)	4m 31s
Build SU2 (ForwardOMP)	3m 29s
Address Sanitizer Tests	0s
Regression Tests	0s
Unit Tests	0s
Thread Sanitizer Tests (hybrid_regression.py)	26m 33s
Thread Sanitizer Tests (hybrid_regression_AD.py)	11m 1s
	2h 19m 11s

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