Non-ascii file names on editor tabs lack filename extension after dot

### Apache NetBeans version

Apache NetBeans 19

### What happened

I have a project with cyrillic filenames with standard filename extensions like 'имя1.txt', 'имя2.sql'. Never have had any issue about that with NetBeans versions prior to 19. Now NetBeans 19 does not display filename extension after the dot on the file tab in the editor. That is, filenames are displayed on the tab like 'имя1.', 'имя2.'. While Project Explorer window does display full file names correctly.

### How to reproduce

_No response_

### Did this work correctly in an earlier version?

Apache NetBeans 18

### Operating System

Windows 10

### JDK

20 OpenJDK

### Apache NetBeans packaging

Apache NetBeans provided installer

### Anything else

Stable problem in NetBeans 19

### Are you willing to submit a pull request?

No

Start by reproducing the issue in Apache NetBeans 19 on Windows 10 with Cyrillic filenames such as имя1.txt and имя2.sql, then compare the editor tabs with NetBeans 18. Confirm that the Project Explorer still shows the full names and that the editor tabs display the extensions after the dot.

Written by the indexing model from the issue text.