Improve callout shortcode. (#31802)

Remove the `markdownify` call, and instead rely on Hugo's proper syntax; `{{% callout %}}` when we want to the content to be processed as Markdown.

This allows for stuff like:

{{% callout info %}}
##### I'm an info callout!

```css
.foo {
  color: #fff;
}
```

{{< example >}}
<div class="alert alert-warning alert-dismissible fade show" role="alert">
  <strong>Holy guacamole!</strong> You should check in on some of those fields below.
  <button type="button" class="btn-close" data-dismiss="alert" aria-label="Close"></button>
</div>
{{< /example >}}
{{% /callout %}}

site/content/docs/5.0/utilities/interactions.md

@@ -26,6 +26,6 @@ Bootstrap provides `.pe-none` and `.pe-auto` classes to prevent or add element i
 <p class="pe-none"><a href="#" tabindex="-1" aria-disabled="true">This link</a> can not be clicked because the <code>pointer-events</code> property is inherited from its parent. However, <a href="#" class="pe-auto">this link</a> has a <code>pe-auto</code> class and can be clicked.</p>
 {{< /example >}}
 
-{{< callout warning >}}
+{{% callout warning %}}
 The `.pe-none` class (and the `pointer-events` CSS property it sets) only prevents interactions with a pointer (mouse, stylus, touch). Links and controls with `.pe-none` are, by default, still focusable and actionable for keyboard users. To ensure that they are completely neutralized even for keyboard users, you may need to add further attributes such as `tabindex="-1"` (to prevent them from receiving keyboard focus) and `aria-disabled="true"` (to convey the fact they are effectively disabled to assistive technologies), and possibly use JavaScript to completely prevent them from being actionable. For form controls, consider using the `disabled` HTML attribute instead.
-{{< /callout >}}
+{{% /callout %}}