[5.2] Fix public folder path when trailing slash is added

[bembelimen]

Summary of Changes

Remove any trailing slashes for public folder path constant

Testing Instructions

• Install a Joomla! 5.2 via the console using a public folder (description here: [5.0] Introduce a CLI UI for creating a public folder #41446 )
• make sure you add a slash at the end of your public folder path
• finish installation
• check e.g. if the scheduler ajax call works (via the browser console)

Actual result BEFORE applying this Pull Request

• error: Site not found

Expected result AFTER applying this Pull Request

• ajax call works
• no trailing slash in the defines.php in your public folder

@dgrammatiko probably you could check if you agree

thanks @HLeithner for helping debugging.

[dgrammatiko]

@bembelimen probably worth mentioning that this happens on windows based OSes

[bembelimen]

I have the problem on a linux server :)