Use correct colours for all system themes

Signed-off-by: TheKodeToad <TheKodeToad@proton.me>

launcher/ui/themes/SystemTheme.h

@@ -38,9 +38,8 @@
 
 class SystemTheme : public ITheme {
    public:
-    SystemTheme(const QString& styleName, const QPalette& palette, bool isDefaultTheme);
+    SystemTheme(const QString& styleName, bool isDefaultTheme);
     virtual ~SystemTheme() {}
-    void apply(bool initial) override;
 
     QString id() override;
     QString name() override;