Remove the deprecated keys from desktop file

Remove the deprecated keys causing the .desktop file to fail validation:

```
./data/desktop/org.xfce.Parole.desktop: warning: key "OnlyShowIn" in group "Desktop Action Play" is deprecated
./data/desktop/org.xfce.Parole.desktop: warning: key "OnlyShowIn" in group "Desktop Action Previous" is deprecated
./data/desktop/org.xfce.Parole.desktop: warning: key "OnlyShowIn" in group "Desktop Action Next" is deprecated
```
2 jobs for !9 with desktop-validate in 2 minutes and 24 seconds
detached
Status Name Job ID Coverage
  Build
passed build #9815

00:00:57

 
  Distcheck
passed distcheck #9816

00:01:26