[CalloutCard] Consolidate se23 logic and styles (#10067)

### WHY are these changes introduced?

Fixes #9924

### WHAT is this pull request doing?

Consolidates se23 beta styles for `CalloutCard`.

### How to 🎩

Compare and make sure they are identical:

* This PR's
[Storybook](https://5d559397bae39100201eedc1-ztjybrtfrh.chromatic.com/?path=/story/all-components-calloutcard--default)
* [Production
Storybook](https://storybook.polaris.shopify.com/?path=/story/all-components-calloutcard--default&globals=polarisSummerEditions2023:true)

polaris-react/src/components/CalloutCard/CalloutCard.scss

@@ -25,17 +25,11 @@
 }
 
 .Title {
-  margin-bottom: var(--p-space-5);
-  #{$se23} & {
-    margin-bottom: var(--p-space-2);
-  }
+  margin-bottom: var(--p-space-2);
 }
 
 .Buttons {
-  margin-top: var(--p-space-5);
-  #{$se23} & {
-    margin-top: var(--p-space-2);
-  }
+  margin-top: var(--p-space-2);
 }
 
 .Container {
@@ -46,7 +40,9 @@
   right: var(--p-space-4);
   top: var(--p-space-4);
   position: absolute;
-  #{$se23} & svg {
+
+  // stylelint-disable-next-line -- Dismiss icon color override
+  & svg {
     fill: var(--p-color-icon-subdued);
   }
 }