chore: disable RemoveVarTagFromClassConstantRector

[kenjis]

Description

The @var tag defines which type of data is represented by a value of a Constant, Property or Variable.
https://github.com/php-fig/fig-standards/blob/master/proposed/phpdoc-tags.md#518-var

It is better that we can write @var to constants like this:

/**
 * @var class-string<Model>
 */
public const $model = Widget::class;

From #4766 (comment)

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[samsonasik]

RemoveVarTagFromClassConstantRector is custom rule, if it disabled, it can also be removed from utils dir if no longer used.

[kenjis]

Removed the file.