Issue #3503041: Fix missing theme_hook_original in preprocess function

Problem/Motivation

When rendering certain views, the preprocess function causes errors because the $variables array is not properly initialized:

Error message:

Error: Undefined array key "theme_hook_original"

Steps to reproduce

• Enable the "Cookies Addons Views" module.
• Create a view with custom templates.
• Load the page and check the PHP error log.

Proposed resolution

Instead of setting $variables = [];, we initialize it with $variables = ['theme_hook_original' => '']; to ensure the key always exists.

Remaining tasks

• Code review
• Manual testing

User interface changes: None.

API changes: None.

Data model changes: None.