fix: correct path parsing in SiteURIFactory::parseRequestURI()

[michalsn]

Description
This PR fixes a bug where route path detection was failing when serving the app from a subfolder using Apache mod_rewrite (to "hide" public directory) while preserving index.php in URL.


So something like: https://localhost/ci/index.php/controller/method - when our real directory structure was like: ci/public/index.php. This caused the route path to return: index.php/controller/method instead of controller/method.



Closes #9607
Fixes #9602




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