fix(spinner): fix default spinner logic for relevant components (#17660)

- In the **`loading`** component, fallback to `spinner` icon config before platform default.
- In both **`refresher`** & **`infinite-scroll`** components, use platform default as final fallback.
- In **`infinite-scroll`** test templates, and the _basic_ **`virtual-scroll`** test template, fix loading _spinner_ and _text_ attributes.

fixes #17659

core/src/components/infinite-scroll-content/infinite-scroll-content.tsx

@@ -30,7 +30,7 @@ export class InfiniteScrollContent implements ComponentInterface {
     if (this.loadingSpinner === undefined) {
       this.loadingSpinner = this.config.get(
         'infiniteLoadingSpinner',
-        this.config.get('spinner', 'lines')
+        this.config.get('spinner', this.mode === 'ios' ? 'lines' : 'crescent')
       );
     }
   }