Fix reassurance slider grid layout fallback

[CySSoO]

Motivation

• Ensure the reassurance prettyblock keeps a multi-column grid when the desktop slider is enabled but the number of items does not require creating carousel slides, avoiding unintended single-column rendering.

Description

• Updated views/templates/hook/prettyblocks/prettyblock_reassurance.tpl to introduce statesCount and expose slider_items_desktop and slider_items_mobile earlier for layout decisions.
• Changed the reassuranceColumnClass condition to treat the desktop slider as a grid when statesCount <= sliderItemsDesktop, so column classes (e.g. 4 per row) are preserved instead of forcing slider-only styling.
• Kept existing carousel rendering paths intact and limited the change to the grid vs slider class selection logic.

Testing

• No automated tests were run for this change.

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Codex Task