Remove 'uglify' from Grunt watch task

The grunt watch task is used by the grunt dev task that watches for
changes and auto rebuilds the editor js.

When running in dev mode, the editor will load the unminified version
of red.js. This means there is no point in running the uglify task to
generate the minified version. The uglify task tasks a few seconds and
if you do a couple rapid saves, the second will often not get built as
the previous uglify task was still running.

Removing it from the dev task shouldn't have any side effects. It still
forms part of the `grunt build` and `grunt release` tasks where it is
needed.

Gruntfile.js

@@ -276,7 +276,7 @@ module.exports = function(grunt) {
                 files: [
                     'packages/node_modules/@node-red/editor-client/src/js/**/*.js'
                 ],
-                tasks: ['copy:build','concat','uglify','attachCopyright:js']
+                tasks: ['copy:build','concat',/*'uglify',*/ 'attachCopyright:js']
             },
             sass: {
                 files: [