[3.x] Don't force html suffix

[BobWez98]

When the catalog/seo/product_url_suffix or catalog/seo/category_url_suffix config setting is set to null this causes the fallback check to return the default because null is a false value.

core/src/Models/Config.php

Line 62 in 4d362bc

return static::getValue($path, options: ['cache' => true, 'decrypt' => $sensitive]) ?? $default;

2.x: #704

[royduin]

Closing in favor of #737