The `site_setting_changed` event passes the setting name as a symbol, not a string. This commit also removes the backwards-compatible `site_setting_saved` event, which was deprecated in 2.3.0.
The `site_setting_changed` event passes the setting name as a symbol, not a string. This commit also removes the backwards-compatible `site_setting_saved` event, which was deprecated in 2.3.0.