Remove unused everblock slider assets

[CySSoO]

Motivation

• The slider implementation is no longer used, so its JavaScript and related CSS can be removed to reduce bundle size and maintenance surface.
• The slider asset should be removed from the allowed file list and not registered by the module to avoid loading dead code.

Description

• Deleted the unused views/js/everblock-slider.js file and removed its code from the project.
• Removed the runtime registration of the slider script in everblock.php so the module no longer enqueues views/js/everblock-slider.js.
• Removed the slider-specific CSS rules from views/css/everblock.css to eliminate unused styles.
• Removed the views/js/everblock-slider.js entry from config/allowed_files.php and verified no remaining in-code references to the slider classes or file paths.

Testing

• No automated tests were executed for this change.

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Codex Task