COs not being deleted -- DEBUG_ASSERT on skin reload

[ronso0]

Bug Description

I've hit this a few times when a skin is recreated, though never cared to investigate.
Actually the COs should be destroyed and recreated with the widget, but they aren't. Or rather they are but the ControlDoublePrivates are not (see https://mixxx.zulipchat.com/#narrow/stream/109171-development/topic/help.20with.20unique_ptr.20.2F.20ControlObjects.20not.20being.20destroyed)

warning [Main] ControlObject "[Channel1]" "stars_up" already created
DEBUG ASSERT: "!"pCreatorCO != nullptr, ControlObject already created"" in function static QSharedPointer<ControlDoublePrivate> ControlDoublePrivate::getControl(const ConfigKey&, ControlFlags, ControlObject*, bool, bool, bool, double) at src/master/src/control/control.cpp:173

Reproduce:

• start Mixxx
• change stars_up of one of the main decks
• reload skin
• DEBUG_ASSERT

vs.

• start Mixxx
• don't touch the stars COs
• reload skins
• no DEBUG_ASSERT
• use one of the stars_up controls
• reload skin
• DEBUG_ASSERT

It happened with these two, both COs are created by widgets

• [Channel1],stars_up from WStarRating here
• [Channel1],end_of_track from VisualsManager here owned by MixxxMainWindow
  Nope, different story, see move COs from DeckVisuals/VisualsManager to BaseTrackPlayerImpl #12593

Version

2.4 + 2.5, probably ever since they were added in 2.3

OS

No response