Refactor preview of osd battery usage

[McGiverGim]

As discussed with @chmelevskij and @haslinghuis here: #2468 this PR does a simply refactor of the preview for osd battery usage.

I liked the @chmelevskij idea, but after implementing @haslinghuis one, I think the first is not necessary. It needs to declare some vars that will be used only at some cases of the switch. After using the repeat I think is enough.

[sonarqubecloud]

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0.0% Duplication

[blckmn]

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