fix(content-gate): change 'paragraph' to 'block' in settings text

[wil-gerken]

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Changes proposed in this Pull Request:

Updated terminology in the content gate settings panel from "paragraph" to "block" to better align with WordPress block terminology.

Since the Content Gate can be applied to any block type, not just paragraphs, this change makes the UI text more accurate and less confusing for users.

Closes # (leave blank - no issue to close).

Closes # .

How to test the changes in this Pull Request:

1. In wp-admin, go here: Audience > Configuration > Content Gating > Content Gate
2. Click on Configure
3. View the Settings in the sidebar to review the copy changes, which are a swap of "paragraph" for "block" on the label: "Default Block Count", and its help: "Number of blocks that readers can see above the content gate.", plus the help on the More tag checkbox: "Override the default block count on pages where a “More” block has been placed."

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

[miguelpeixe]

I'm not sure we should make this change. It counts only paragraphs when calculating the visible content for gated articles:

newspack-plugin/includes/content-gate/trait-content-gate-layout.php

Lines 163 to 167 in c8428a6

	$count = max( 1, (int) \get_post_meta( $gate_post_id, 'visible_paragraphs', true ) );
	// Split into paragraphs.
	$content = explode( '</p>', $content );
	// Extract the first $x paragraphs only.
	$content = array_slice( $content, 0, $count ?? 2 );

Changing the terminology can be misleading.