[REF] web_editor: remove useless code in palette

Previously the widget was not refreshed everytime it was opened.
Now that it is the case and since the color picker rerenders every time
we select a color:
It is no longer required to select/unselect the colors.
It is no longer required to add custom colors to existing colors.

Part of: https://github.com/odoo/odoo/pull/45872

task-2212288

closes odoo/odoo#47355

X-original-commit: 481fe703e9400fb64e96291914f76d4dca883e29
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web_editor/static/src/js/wysiwyg/widgets/color_palette.js

@@ -171,11 +171,7 @@ const ColorPaletteWidget = Widget.extend({
         if (this.options.excluded.includes('custom')) {
             return;
         }
-        const existingColors = new Set(this.summernoteCustomColorsArray.concat(
-            [...this.el.querySelectorAll('.o_custom_color')].map(el => {
-                return ColorpickerDialog.normalizeCSSColor(el.style.backgroundColor);
-            })
-        ));
+        const existingColors = new Set(this.summernoteCustomColorsArray);
         this.trigger_up('get_custom_colors', {
             onSuccess: (colors) => {
                 colors.forEach(color => {
@@ -265,8 +261,6 @@ const ColorPaletteWidget = Widget.extend({
      */
     _onColorButtonClick: function (ev) {
         const buttonEl = ev.currentTarget;
-        this.$('button.selected').removeClass('selected');
-        $(buttonEl).addClass('selected');
         const colorInfo = this._getButtonInfo(buttonEl);
         this._selectColor(colorInfo);
     },
@@ -307,7 +301,6 @@ const ColorPaletteWidget = Widget.extend({
      * @param {Event} ev
      */
     _onColorResetButtonClick: function (ev) {
-        this.$('button.selected').removeClass('selected');
         this.selectedColor = false;
         this.trigger_up('color_reset', {
             target: ev.target,
@@ -329,7 +322,6 @@ const ColorPaletteWidget = Widget.extend({
             defaultColor: selectedColor,
         });
         colorpicker.on('colorpicker:saved', this, ev => {
-            this.$('button.selected').removeClass('selected');
             this._selectColor({
                 color: ev.data.cssColor,
                 target: target,