Add regression test for scala#22076 (scala#22602)

Closes scala#22076.

---------

Co-authored-by: Sébastien Doeraene <[email protected]>
[Cherry-picked a601e83]

Author: mbovel

tests/pos/match-type-disjoint-22076.scala

@@ -0,0 +1,8 @@
+trait Foo[CP <: NonEmptyTuple]:
+  type EndNode = Tuple.Last[CP]
+
+def f(end: Foo[?]): end.EndNode =
+  ???
+
+trait Bar[CP <: NonEmptyTuple] extends Foo[CP]:
+  val v: EndNode = f(this)