ComboboxControl: Replace undefined variable usage with color-mix for disabled selection#69621

ciampo merged 4 commits intoWordPress:trunkWordPress/gutenberg:trunkfrom

yogeshbhutkar:fix-69593/combobox-control-disabled-stateyogeshbhutkar/gutenberg:fix-69593/combobox-control-disabled-stateCopy head branch name to clipboard