i18n: show "1 more reply" instead of "1 more replies" in block comments

[R1shabh-Gupta]

What?

Closes #71684

Fixes the grammatical error in block commenting where "1 more replies" was displayed instead of the correct singular form "1 more reply".

Why?

When there is exactly one hidden reply in a comment thread, the interface incorrectly shows "1 more replies" which is grammatically wrong. It should show "1 more reply" (singular) for one reply and "X more replies" (plural) for multiple replies. This improves the user experience and ensures proper grammar across all languages that support WordPress pluralization.

How?

• Replaced _x() function with _n() function in the comments component
• Added proper singular and plural forms: '%s more reply' and '%s more replies'

Testing Instructions

1. Open the WordPress editor (post or page)
2. Add a block (any block type works)
3. Add at least 2 comments to the block
4. Verify that when there's exactly 1 hidden reply, it shows "1 more reply"
5. Verify that when there are 2 or more hidden replies, it shows "X more replies"

Screenshots or screencast

Before	After

[github-actions]

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Co-authored-by: R1shabh-Gupta <rishabhwp@git.wordpress.org>
Co-authored-by: ramonjd <ramonopoly@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>

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[t-hamano]

I just merged #71387.

@R1shabh-Gupta, could you please rebase this branch on top of the trunk? The text is now placed inside a Button component, so it would be great if you could test it again just to be sure.

[R1shabh-Gupta]

Hey @t-hamano,
I’ve rebased the branch and tested it with the updated Button component. Everything is working as expected. ✅

[t-hamano]

LGTM!