Remove the extra font-size override for the select control on medium layouts

[sejas]

What?

Closes #70617

The input control changes the font-size when the viewport is lower than 600px but the SelectControl changes before, at 782px. I think this is an error and this PR fixes it and makes the SelectControl consistent to the regular input.

Change introduced at #10957.

Why?

It's weird to see the select control change the font-size when the rest of the compnents stay the same.

How?

Testing Instructions

• Run npm run storybook:dev
• Access http://localhost:50240/?path=/docs/components-selectcontrol--docs
• Reduce the width of the window to 1082
• Observe nothing changes
• Reduce the width of the window to 900
• Observe the select control font-size changes. It behaves the same as the title and the other input components.

select-control-changes-at-the-same-width-as-input-control.mp4

Testing Instructions for Keyboard

N/A

Screenshots or screencast

Before	After

[github-actions]

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Co-authored-by: sejas <antoniosejas@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>

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[t-hamano]

LGTM! This CSS is no longer needed, but I guess we forgot to remove it.

Could you add an entry to the CHANGELOG file? Perhaps this would fit in the Bug Fixes section.

[sejas]

Could you add an entry to the CHANGELOG file? Perhaps this would fit in the Bug Fixes section.

@t-hamano , thanks for the review and the suggestions. I added an entry in the changelog 2ce72cd