[Task Manager] Prefer PID match even when desktop entry doesn't match

When an application got renamed by flatpak-builder without knowing it, it will still send
its original value as desktop-entry breaking the mapping.
If the PID of the service matches the window owner's PID imho it's fine to assume it's a match.

CHANGELOG: More reliable Task Manager media controls for application bundles

Differential Revision: https://phabricator.kde.org/D22060