fix(accordion): update design and tokens (#30606)

Issue number: internal
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## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->
- update tokens;
- fix item content padding;

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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  2. Update the BREAKING.md file with the breaking change.
3. Add "BREAKING CHANGE: [...]" to the commit description when merging.
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## Other information

<!-- Any other information that is important to this PR such as
screenshots of how the component looks before and after the change. -->

[basic](https://ionic-framework-git-rou-12135-ionic1.vercel.app/src/components/accordion/test/basic?ionic:theme=ionic)

[states](https://ionic-framework-git-rou-12135-ionic1.vercel.app/src/components/accordion/test/states?ionic:theme=ionic)
[Group
States](https://ionic-framework-git-rou-12135-ionic1.vercel.app/src/components/accordion-group/test/states?ionic:theme=ionic)

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Co-authored-by: ionitron <hi@ionicframework.com>

core/src/css/ionic/core.ionic.scss

@@ -290,7 +290,7 @@ ion-card-header.ion-color .ion-inherit-color {
 // The toggle icon is nested in the accordion item so we need to
 // style it from a global level.
 ion-accordion > [slot="header"] .ion-accordion-toggle-icon {
-  color: globals.$ion-primitives-neutral-1000;
+  color: globals.$ion-icon-default;
   font-size: globals.$ion-scale-600;
 }