fix(core): comment empty style issue (#13208)

fix BS-3618

#### PR Dependency Tree


* **PR #13208** 👈

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[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit

* **Style**
* Improved the appearance of the empty state in the comment sidebar by
centering the text and adjusting line spacing for better readability.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/components/comment/sidebar/style.css.ts

@@ -42,6 +42,8 @@ export const empty = style({
   padding: 32,
   display: 'flex',
   alignItems: 'center',
+  textAlign: 'center',
+  lineHeight: '24px',
   justifyContent: 'center',
   color: cssVarV2('text/secondary'),
 });