Social Links: Remove redundant reduce-motion mixin

[himanshupathak95]

Part of / Closes: #68282
Follow up: #68282 (comment)

What?

Removes redundant reduce-motion mixin from social links incomplete state in editor styles.

Why?

In the social links editor styles, we had a reduce-motion mixin applied to the incomplete social link state (wp-social-link__is-incomplete). However, this mixin was unnecessary because:

• There is no explicit opacity transition defined that needs to be disabled
• The only animation (transform on hover) is already properly handled with a media query in style.scss
• The opacity change is instant by default

Testing Instructions

1. In the editor, add a Social Links block
2. Click the "+" button to start adding a new social link but don't complete it
3. Verify the incomplete social link appears semi-transparent (opacity: 0.5)
4. Test opacity changes - Hover over the incomplete link - it should become fully opaque

Test motion preferences:

1. Enable "Emulate CSS media feature prefers-reduced-motion: reduce"
2. Verify the opacity change remains instant

Screencast

Screen.Recording.2025-02-03.at.10.29.07.mov

[himanshupathak95]

Hey @t-hamano, Thanks for pointing this issue out.

I see that the mixing @include reduce-motion("transition"); was added in #18750 to respect the user's preferences of motion handling.

I found that the incomplete link state never defined an explicit transition for the opacity property - the opacity change was always instant. The only actual transition in social links (the transform/scale effect on hover) is already properly handled with a media query in style.scss.

The mixin was essentially a no-op since it was setting transition duration/delay to 0s for a transition that didn't exist.
I've tested the transition with the motion enabled and disabled, it seems to be fine. Let me know if it looks good to you.

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Co-authored-by: himanshupathak95 <[email protected]>
Co-authored-by: mirka <[email protected]>
Co-authored-by: Mayank-Tripathi32 <[email protected]>
Co-authored-by: t-hamano <[email protected]>

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[t-hamano]

I tested some older versions of WordPress and the opacity animations didn't seem to work at all, so I think it's safe to remove this mixin.