TextEditor: Update circular clipboard on cut

Task-number: QTCREATORBUG-8713
Change-Id: Ic83c78a4caf7f768259c8f6830e7b81016c70e5e
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>
Reviewed-by: David Schulz <david.schulz@digia.com>