chore(analysis/convex/basic): generalize `concave_on.le_on_segment` to monoids (#8959)
chore(analysis/convex/basic): generalize `concave_on.le_on_segment` to monoids (#8959)

This matches the generalization already present on `convex_on.le_on_segment`.





leanprover-community/mathlib,leanprover-community/mathlib