[TypeChecker] NFC: Remove resurrected use of SolverShrinkUnsolvedThreshold

Author: xedin

include/swift/Sema/ConstraintSystem.h

@@ -2521,9 +2521,8 @@ class ConstraintSystem {
         }
       }
 
-      unsigned threshold =
-          cs->getASTContext().TypeCheckerOpts.SolverShrinkUnsolvedThreshold;
-      return unsolvedDisjunctions >= threshold;
+      // The threshold used to be `TypeCheckerOpts.SolverShrinkUnsolvedThreshold`
+      return unsolvedDisjunctions >= 10;
     }
   };