fix(tab-button): fix font-size token on ionic theme (#30439)

Issue number: internal

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## What is the new behavior?
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- Updated typography to use correct token.

## 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
tab-bar](https://ionic-framework-git-rou-11968-tabs-ionic1.vercel.app/src/components/tab-bar/test/basic?ionic:theme=ionic)

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