[Bug] Fix memory allocation test in CAGRA graph optimization

[enp1s0]

rel: #1619

The actual memory allocation is performed by make_device_mdarray, so the corresponding memory allocation test should also be done using this function. However, the current code uses make_device_matrix for the test.

This PR fixes this inconsistency.

In the same source file, d_detour_count and d_num_no_detour_edges are allocated via make_device_mdarray, and d_input_graph is allocated through device_matrix_view_from_host (defined in cpp/src/neighbors/detail/cagra/utils.hpp), which internally calls make_device_mdarray.

[cjnolet]

/merge