Input Control: Remove mobile-specific font size override in input controls

[himanshupathak95]

What?

Closes: #69113

Removes mobile-specific font size override in input controls to maintain consistent typography across screen sizes.

Why?

Currently, there's an inconsistency in font sizes on mobile screens where the selected text in custom select controls appears at 16px while other elements remain at 13px. This creates:

• Visual disruption in typography hierarchy
• Inconsistency between selected text (16px) and dropdown options (13px)
• Unnecessary variation from other form controls and text elements

Testing Instructions

• Open any page/post with a custom select control (e.g., the Typography panel in the block editor)
• View the page at mobile width (below 600px)
• Verify that:
  • The selected text in dropdowns is now 13px (consistent with other elements)
  • The dropdown options remain at 13px
  • The text appears visually consistent with other form controls

Screencast

Before

Screen.Recording.2025-02-10.at.13.15.06.mov

After

Screen.Recording.2025-02-10.at.13.31.50.mov

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Co-authored-by: himanshupathak95 <[email protected]>

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