Remove tst_qquicktextinput::horizontalAlignment()

These tests are not valid. Will be covered by Lancelot-based scenegraph
rendering tests: https://codereview.qt-project.org/#change,34437



Change-Id: I1bb6261d7849ec00e23acce496c1e2e61152322e
Reviewed-by: Sergio Ahumada <sergio.ahumada@nokia.com>
Reviewed-by: Caroline Chao <caroline.chao@nokia.com>
Reviewed-by: Yoann Lopes <yoann.lopes@nokia.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@nokia.com>