Desktop: Fixes #10672: External editing: Fix notes often not updated when saved from Vim

[personalizedrefrigerator]

Summary

This pull request fixes #10672 by removing an outdated workaround for a resolved upstream issue.

Testing plan

1. Set gvim as the external editor.
2. Open a note.
3. Click the "open in external editor" button.
4. Make a change.
5. Save with :w.
6. Verify that the change is visible in Joplin.
7. Repeat steps 4-6 for 2-3 more small changes.
8. Set the external editor to gnome-text-editor (/usr/bin/gnome-text-editor for me).
9. Open two notes using the "toggle external editor" button.
10. Make changes to both notes from gnome-text-editor and save.
11. Verify that both changes are shown in Joplin.

This has been tested successfully on Ubuntu 24.04.