Partially revert porting away from serviceOwnerChanged signal

Authored by dvratil on Jan 5 2020, 2:17 PM.

Description

Partially revert porting away from serviceOwnerChanged signal

This reverts commits 5242bf2718e47e8e72007c6ff04dfb8d24031195
(D26274) and 8b879883f39037810c2da94779a6628ec37a6259 (D26282).

The QDBusServiceWatcher support for wildcard service watching
has been introduced in Qt 5.13, which we cannot depend on
yet. For now we have to revert to the deprected serviceOwnerChanged()
signal in those cases.

Details