Spacing presets: Prevent % spacing size units being stripped by sanitize_title

[glendaviesnz]

What?

Fixes bug with % unit setting in spacingScale values in theme.json not working

Why?

% is supposed to be a valid unit for spacing sizes. sanitize_title`

How?

Adds a ternary to prevent a spacing sizes preset unit of % being passed through sanitize_title

Testing Instructions

• Modify the unit in lib/compat/wordpress-6.1/theme.json in settings.spacing.spacingScale.unit to %
• Add the following block code to editor, and make sure percentage padding values show correctly in editor and frontend

<!-- wp:group {"style":{"spacing":{"padding":{"top":"var:preset|spacing|40","right":"var:preset|spacing|70","bottom":"var:preset|spacing|30","left":"var:preset|spacing|50"}}},"backgroundColor":"vivid-red","textColor":"background"} -->
<div class="wp-block-group has-background-color has-vivid-red-background-color has-text-color has-background" style="padding-top:var(--wp--preset--spacing--40);padding-right:var(--wp--preset--spacing--70);padding-bottom:var(--wp--preset--spacing--30);padding-left:var(--wp--preset--spacing--50)"><!-- wp:paragraph -->
<p>Percent should work</p>
<!-- /wp:paragraph --></div>
<!-- /wp:group -->

Screenshots

Before:

After:

[scruffian]

LGTM