flatpak: Use -Dbattery_detection=none for tracker-miners

The flatpak jobs are broken currently, because the tracker-miners project fails to build due to missing upower-glib depenedency. It is used to tweak the behavior when running on battery. It used to be automatically disabled until the following MR: !1121 (merged). I suppose it is safe to disable this functionality as our flatpak isn't meant for production. Let's explicitely disable that to fix our pipeline.