Correct active file highlight in Template Manager

[SharkyKZ]

Pull Request for Issue #25395.

Summary of Changes

Corrects active file detection in file editor.

Testing Instructions

Create two files in template directory. One file name should contain the file name of another file. E.g. menu.php and newmenu.php.
Edit menu.php in Template Manager.
Check highlighted files on the left.

Expected result

menu.php highlighted.

Actual result

menu.php and newmenu.php are highlighted.

Documentation Changes Required

No.

[n9iels]

I have tested this item ✅ successfully on e59a420

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/25399.}

[richard67]

I have tested this item ✅ successfully on e59a420

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/25399.}

[ghost]

Status "Ready To Commit".

[HLeithner]

thx