This commit replaces the allow_community_topic_editing boolean with
integer field edit_topic_policy and includes both frontend and
backend changes.
We also update settings_ui.disable_sub_settings_onchange to not
change the color of label as we did previously when the setting
was a checkbox. But now as the setting is dropdown we keep the
label as it is and we don't do anything with label when disabling
dropdowns. Also, this function was used only here so we can safely
change this.
sahil839