fix(element-theme): reduce button padding to align with design specs

[ljanner]

Resolves #1801

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Documentation.
Examples.
Dashboards Demo.
Playwright report.

Coverage Reports:

• charts-ng
• dashboards-ng
• element-ng
• element-translate-ng
• maps-ng
• native-charts-ng

[gemini-code-assist]

Code Review

This pull request updates button styling by reducing horizontal padding and refactoring icon margins, which resulted in updated visual snapshots. A review comment suggests that the current use of margin-inline-end on icons may lead to asymmetrical spacing when an icon is the trailing element; it recommends using the gap property on the button container or applying conditional margins to ensure consistent spacing regardless of the icon's position.

[github-actions]

⬇️ Download VRTs

[ljanner]

I've opted to do the snapshot updates in the same commit as the change itself, because from my understanding this is the preferred way. Additionally I used element-theme as a scope as this is where the change takes place, but I can also see the argument to use buttons as a scope instead.

[panch1739]

@ljanner A masterpiece, a delight to the sight, the most magical PR i have seen in my life.