Drop non-sensical case in provablyDisjoint

Surely, two intersection types A1 & A2 and B1 & B2 are provable disjoint
if any pair of A_i and B_j is provably disjoint? This is already handled
by the single-side cases for AndTypes. The dropped case imposed
a stronger condition.

Author: odersky

compiler/src/dotty/tools/dotc/core/TypeComparer.scala

@@ -2413,9 +2413,6 @@ class TypeComparer(initctx: Context) extends ConstraintHandling[AbsentContext] w
         provablyDisjoint(tp1.tp1, tp2) && provablyDisjoint(tp1.tp2, tp2)
       case (_, tp2: OrType)  =>
         provablyDisjoint(tp1, tp2.tp1) && provablyDisjoint(tp1, tp2.tp2)
-      case (tp1: AndType, tp2: AndType) =>
-        (provablyDisjoint(tp1.tp1, tp2.tp1) || provablyDisjoint(tp1.tp2, tp2.tp2)) &&
-        (provablyDisjoint(tp1.tp1, tp2.tp2) || provablyDisjoint(tp1.tp2, tp2.tp1))
       case (tp1: AndType, _) =>
         !(tp1 <:< tp2)
         && (provablyDisjoint(tp1.tp2, tp2) || provablyDisjoint(tp1.tp1, tp2))