Publish the KIO slave on hold immediately after putting it on hold to avoid
freezing the entire KDE desktop.

This effectively restores commit cf2e569c0faa1858d27d1318df7c6ebc2d61d1ba,
which got reverted in another commit b8a35694b1225fb4e4fc9a43f75bc96351530539,
because now publishing the KIO slave immediately after putting it on hold
works as intended.