coincontrol: Replace HasInputWeight with returning optional from Get

src/wallet/test/fuzz/coincontrol.cpp

@@ -76,10 +76,7 @@ FUZZ_TARGET(coincontrol, .init = initialize_coincontrol)
                 (void)coin_control.SetInputWeight(out_point, weight);
             },
             [&] {
-                // Condition to avoid the assertion in GetInputWeight
-                if (coin_control.HasInputWeight(out_point)) {
-                    (void)coin_control.GetInputWeight(out_point);
-                }
+                (void)coin_control.GetInputWeight(out_point);
             });
     }
 }