Update sentence related to handling the Universal Discovery Widget.

In https://github.com/ezsystems/PlatformUIBundle/pull/795 the new approach to the UDW has been merged.
This change renders the existing Behat sentence handling the UDW incompatible.
It is required to reimplement the Behat UDW sentence.

Error from logs:
Exception: Timeout while retreaving DOM element. Last exception: Element with selector '.ez-view-universaldiscoverybrowseview .ez-ud-browse-tree' was not found in vendor/ezsystems/platform-ui-bundle/Features/Context/PlatformUI.php:217
Originates from $node = $this->findWithWait('.ez-view-universaldiscoverybrowseview .ez-ud-browse-tree', $node); in selectFromUniversalDiscovery($path) in Features/Context/SubContext/CommonActions.php.