Fix MPRIS Play

Summary: Like D11373 and D11467, but for play, which suffers from the same issue

Test Plan: Inspect with QDBusViewer, trigger play, pause and playpause in various sequences

Reviewers: Elisa, mgallien

Reviewed By: Elisa, mgallien

Subscribers: mgallien, Elisa

Tags: Elisa

Differential Revision: https://phabricator.kde.org/D11556