Select highest default perk on price change on Donation page

As per conversation with Richard and Peter to be applied
on the donate page.

Issue #48575

parcel/js/giving_form.jsx

@@ -80,13 +80,10 @@ export function _GivingForm(props) {
 
   const onPriceChange = (price) => {
     setSelectedPrice(price);
-    if (!noPerk) {
-      if (price < getPerkPrice(selectedPerk) || !selectedPerk) {
-        setSelectedPerk(getDefaultPerk(price));
-      }
-    }
-    if (getDefaultPerk(price) == null) {
+    if (getDefaultPerk(price) == null || noPerk) {
       setNoPerk(true);
+    } else {
+      setSelectedPerk(getDefaultPerk(price));
     }
   }