mathlib3

1ef34126 - refactor(order/rel_classes): ditch `is_strict_total_order'` (#16069)

refactor(order/rel_classes): ditch `is_strict_total_order'` (#16069) Since Lean 3.46, `is_strict_total_order` and `is_strict_total_order'` are exactly the same typeclass. Hence, we remove the latter for the former. Co-authored-by: Yury G. Kudryashov <urkud@urkud.name>