Aggregation threshold needs to be a scalar.
ML: Removing semicoarsening warning output if you're not semicoarsening

Build/Test Cases Summary
Enabled Packages: ML
0) MPI_DEBUG => passed: passed=33,notpassed=0 (24.98 min)
1) SERIAL_RELEASE => passed: passed=32,notpassed=0 (7.51 min)
Kokkos: Support subview from LayoutLeft-Rank-2 to LayoutLeft-Rank-2 with arguments( pair , index ).  Needed by Tpetra multivector.