Uneeded since the merge of most of the KDE5FilePicker code into
Qt5FilePicker. KDE5SalInstance also uses no signals or slots, so
Q_OBJECT + moc can go for them.

Change-Id: If48c677106b78c759ca165563ad3c081ca5442a5
Reviewed-on: https://gerrit.libreoffice.org/73393
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>