Limit initial OpenBLAS thread count (#46844)
* Limit initial OpenBLAS thread count
We set OpenBLAS's initial thread count to `1` to prevent runaway
allocation within OpenBLAS's initial thread startup. LinearAlgebra will
later call `BLAS.set_num_threads()` to the actual value we require.
* Support older names
(cherry picked from commit 58b559f4a238faeeac03fbdec181ededd27053bc)