Pass on `RealT` in `TreeMesh` construction #10980

Job	Run time
tree_part1 - ubuntu-latest - x64	19s
tree_part2 - ubuntu-latest - x64	21s
tree_part3 - ubuntu-latest - x64	20s
tree_part4 - ubuntu-latest - x64	19s
tree_part5 - ubuntu-latest - x64	20s
tree_part6 - ubuntu-latest - x64	20s
structured - ubuntu-latest - x64	20s
p4est_part1 - ubuntu-latest - x64	19s
p4est_part2 - ubuntu-latest - x64	20s
t8code_part1 - ubuntu-latest - x64	21s
t8code_part2 - ubuntu-latest - x64	20s
unstructured_dgmulti - ubuntu-latest - x64	19s
parabolic - ubuntu-latest - x64	20s
paper_self_gravitating_gas_dynamics - ubuntu-latest - x64	20s
misc_part1 - ubuntu-latest - x64	20s
misc_part2 - ubuntu-latest - x64	20s
performance_specializations_part1 - ubuntu-latest - x64	20s
performance_specializations_part2 - ubuntu-latest - x64	20s
mpi - ubuntu-latest - x64	21s
threaded - ubuntu-latest - x64	22s
threaded_legacy - ubuntu-latest - x64	1s
threaded_legacy - ubuntu-latest - x64	1s
mpi - macos-13 - x64	20s
threaded - macos-latest - aarch64	21s
mpi - windows-latest - x64	9s
threaded - windows-latest - x64	17s
finish	1s
	7m 51s

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