Minimize test case

Author: lorchrob

tests/regression/falsifiable/ref_ty_ghost.lus

@@ -1,12 +1,5 @@
 type Pos = subtype { x: int | x >= 1 }; 
 
-contract C () returns (out: int);
-let
-  var l: Pos = 0;
-  const c: Pos = 0;
-  guarantee true;
-tel
-
 function imported F() returns (x: int);
 con
   var l: Pos = 0;