Tests failing on Sunspot

[aprokop]

Clustering test fails on Sunspot. There are two issues:

1. Rounding off error in DBSCAN (#1112)
2. Dendrogram failure

   <snip>arborx/test/tstDendrogram.cpp(187): error:
   in "Dendrogram/dendrogram_boruvka<Kokkos__Device<Kokkos__Experimental__SYCL_ Kokkos__Experimental__SYCLDeviceUSMSpace>>":
   check parents_boruvka == parents_union_find has failed
   - mismatch at position 0: [856 == 115] is false
   - mismatch at position 1: [747 == 14] is false
   - mismatch at position 2: [251 == 152] is false
   - mismatch at position 3: [956 == 494] is false

I'm not sure what causes the dendrogram failure yet. The test is not robust in the presence of same weight edges, but it would be weird if it occured here.

[masterleinad]

With #1112, all tests (configuring without MPI) pass for me.

[masterleinad]

The culprit seems to be not specifying -fp-model=precise.

[aprokop]

The culprit seems to be not specifying -fp-model=precise.

Release with -fp-model=precise works. RelWithDebInfo with -fp-model=precise fails.

[aprokop]

Release with -fp-model=precise works. RelWithDebInfo with -fp-model=precise fails.

@masterleinad Is this something you can look at?