[REG 3.2.2 -> 3.3.0] Renaming files in Project tree takes too long

1. Open a project.
2. In Projects view, right-click a file and select "Rename..." from the menu.
3. Type a new file name and press Enter.
   Creator will reset the shown file name to the previous state for about three seconds. Then it will display the new name.

Creator should show the new file name. The file should be renamed in the file system. The file name should be updated in the pro-file. All this should happen immediately. This worked correctly with Creator 3.2.

Found by Squish test tst_rename_file.