remove unused file (#6440)

frontend/src/metabase/admin/settings/components/widgets/PremiumEmbeddingWidget.jsx

-import React, { Component } from "react";
-
-import MetabaseSettings from "metabase/lib/settings";
-
-import SettingInput from "./SettingInput.jsx";
-
-export default class PremiumEmbeddingWidget extends Component {
-    render() {
-        return (
-            <div>
-                <SettingInput {...this.props} />
-                <h3 className="mt4 mb4">
-                    Getting your very own premium embedding token
-                </h3>
-                <a href={MetabaseSettings.metastoreUrl()} target="_blank">
-                    Visit the MetaStore
-                </a>
-            </div>
-        );
-    }
-}