Fix TextInput and TextEdit openInputPanel autotests

Fix TextInput and TextEdit openInputPanel autotests

Task-number: QTBUG-21691

The change also removes showInputPanelOnClick code from the TextInput and
TextEdit, which was done to support Symbian^1 and ^3 fullscreen keyboards.
Now by default the keyboard always follows editor focus.

Change-Id: Id60a17fe51b3aa49ba9ea81b985e608e91c26145
Reviewed-on: http://codereview.qt-project.org/5733
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Andrew den Exter <andrew.den-exter@nokia.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>