number of library items not fully displayed -> show as tooltip

From jabref created by [ghost](https://github.com/ghost): JabRef/jabref#10208

### JabRef version

5.9 (latest release)

### Operating system

Windows

### Details on version and operating system

Windows 10 22H2

### Checked with the latest development build

- [X] I made a backup of my libraries before testing the latest development version.
- [X] I have tested the latest development version and the problem persists

### Steps to reproduce the behaviour

I have downloaded 2 databases in BibTeX format: one is an arcade game database (45974 items), the other a game console/computer database (134352)

Please look at screenshot. The number of items in the library is not fully displayed (see at the left). Only 4 digits are displayed, the rest in front of it is gone. Could it be fixed so I see the currect number of items? I know it are A LOT but it's possible to have such a big library :)



Attached are the 2 bib files

[games.zip](https://github.com/JabRef/jabref/files/12431909/games.zip)

### Appendix

...

Log File

```
Paste an excerpt of your log file here
```

Start by reproducing the truncated library item count in JabRef with the attached large BibTeX files, then trace the desktop UI element that displays the count. Done means the full number is visible, such as through a tooltip, without breaking the existing library view.

Written by the indexing model from the issue text.