Remove validation demo code

This is example code from @ara4n's work in
matrix-org#2550. We're not ready to
actually apply validation yet, so removing this for now.

src/components/views/auth/ServerConfig.js

@@ -90,15 +90,6 @@ export default class ServerConfig extends React.PureComponent {
         this.setState({ hsUrl });
     }
 
-    onHomeserverValidate = (value) => {
-        try {
-            new URL(value);
-            return { valid: true, feedback: <div>Valid URL!</div> };
-        } catch (_) {
-            return { valid: false, feedback: <div>Invalid URL!</div>};
-        }
-    }
-
     onIdentityServerBlur = (ev) => {
         this._isTimeoutId = this._waitThenInvoke(this._isTimeoutId, () => {
             this.props.onServerConfigChange({
@@ -143,7 +134,6 @@ export default class ServerConfig extends React.PureComponent {
                         value={this.state.hsUrl}
                         onBlur={this.onHomeserverBlur}
                         onChange={this.onHomeserverChange}
-                        onValidate={this.onHomeserverValidate}
                     />
                     <Field id="mx_ServerConfig_isUrl"
                         label={_t("Identity Server URL")}