Revert "Tune zio buffer caches and their alignments"

This reverts commit bd7a02c251d8c119937e847d5161b512913667e6 which
can trigger an unlikely existing bio alignment issue on Linux.
This change is good, but the underlying issue it exposes needs to
be resolved before this can be re-applied.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #15533