UI: Fix crash when toggling volume control mode

The toggleControlLayoutAction (change between horizontal and vertical
display mode) deletes and re-recreates the volume controls, meaning we
were writing to freed memory. This is a kind of hacky fix but it's the
only action we need to be concerned with for now.
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Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f