kcms/colors: Fix un-setting accent color from wallpaper

Fix changes in 6e7a147e3, where the property `accentColorFromWallpaper`
would get set but not un-set from the UI.

kcms/colors/colors.cpp

@@ -72,6 +72,7 @@ KCMColors::KCMColors(QObject *parent, const KPluginMetaData &data, const QVarian
     });
 
     connect(colorsSettings(), &ColorsSettings::accentColorChanged, this, &KCMColors::accentColorChanged);
+    connect(colorsSettings(), &ColorsSettings::accentColorFromWallpaperChanged, this, &KCMColors::accentColorFromWallpaperChanged);
 
     connect(m_model, &ColorsModel::selectedSchemeChanged, m_filteredModel, &FilterProxyModel::setSelectedScheme);
     m_filteredModel->setSourceModel(m_model);

kcms/colors/package/contents/ui/main.qml

@@ -146,6 +146,7 @@ KCM.GridViewKCM {
 
                 onToggled: {
                     if (checked) {
+                        kcm.accentColorFromWallpaper = false;
                         kcm.accentColor = "transparent"
                     }
                 }
@@ -171,6 +172,7 @@ KCM.GridViewKCM {
 
                     onToggled: {
                         if (checked) {
+                            kcm.accentColorFromWallpaper = false;
                             kcm.accentColor = colorRepeater.model[0]
                         }
                     }
@@ -237,9 +239,10 @@ KCM.GridViewKCM {
                             checked: Qt.colorEqual(kcm.accentColor, modelData)
 
                             onToggled: {
+                                kcm.accentColorFromWallpaper = false;
                                 kcm.accentColor = modelData
                                 checked = Qt.binding(() => Qt.colorEqual(kcm.accentColor, modelData));
-                                }
+                            }
                         }
                     }