Refactor: CodeIgniter::generateCacheName()

[iRedds]

Description
Optimizing the code for getting the URL in the CodeIgniter::generateCacheName() method.
The change uses cloning the URL object and modifying the properties, instead of calling URI::createURIString() directly with arguments.

The code is more compact.

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

[MGatner]

Much cleaner, thank you @iRedds