fix(modal): fix color tokens on ionic theme (#30379)

Issue number: internal

---------

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## What is the new behavior?
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this PR. -->

- Fixed the tokens used on background and text.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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screenshots of how the component looks before and after the change. -->

- [Ionic Custom
Dialog](https://ionic-framework-git-rou-11900-ionic1.vercel.app/src/components/modal/test/custom-dialog?ionic:theme=ionic)

core/src/components/modal/modal.ionic.scss

@@ -5,12 +5,12 @@
 // --------------------------------------------------
 
 :host {
-  --background: #{globals.$ion-primitives-base-white};
+  --background: #{globals.$ion-bg-surface-default};
   --box-shadow: #{globals.$ion-elevation-3};
   // Backdrop opacity is 1 because the backdrop's background color has an alpha value
   --backdrop-opacity: 1;
 
-  color: globals.$ion-primitives-neutral-1200;
+  color: globals.$ion-text-default;
 }
 
 // Shape